Error P0420 - what it means, symptoms, causes, diagnosis, solution

Are you trying to get rid of the P0420 error code? Then this article is for you. The P0420 fault can be difficult to diagnose. You think you have fixed the error, but after 100 km the Check Engine light comes on again.

This code is triggered when the engine control module detects a faulty catalytic converter. It uses one oxygen sensor at the front of the exhaust manifold - before the catalyst, and another oxygen sensor - after the catalytic converter to measure the efficiency of the catalyst.

In this article, you will learn everything you need to know about the P0420 code to fix it once and for all.

What does code P0420 mean?

P0420 is triggered in the Electronic Control Unit (ECU) when there is a problem with the performance of the catalytic converter. The controller uses two oxygen sensors - one before and one after the catalyst to measure its efficiency. The error occurs if the converter or oxygen sensor malfunctions, which begins to transmit incorrect data.

We receive many messages asking about the P0420 code. It keeps coming back after several repairs and you just end up spending more and more money on auto repair work. This trouble code may confuse you because there is a lot of misinformation about it.

Catalytic converter

• The front O2 sensor measures the air-fuel mixture. It tells the control unit if the engine is running rich or lean.
• The rear O2 sensor is the diagnostic oxygen sensor for this error code.

If the rear oxygen sensor receives incorrect values, a P0420 fault will be stored in the ECU. This could be due to a faulty catalytic converter or one of the O2 sensors failing. There may also be many other problems with the engine that are destroying the catalytic converter, and if you install a new one, it may be damaged again.

The oxygen sensor is also called a lambda probe.

Many people think that a lean or rich mixture can cause this error code. Yes, it is possible, but not in the way you think. A rich or lean mixture can damage the catalytic converter and when it is damaged/full of fuel it will be low in efficiency and the rear oxygen sensor will see this and trigger a P0420 code.

P0420 - time to change the catalyst?

The most correct and reasonable way is to replace the catalyst.
For most cars older than 10 years (and this error is unlikely to occur on “new” cars), the cost of the catalyst is not that high. On analysis sites and online sites, the price of a used catalyst starts from 3-5 thousand rubles. Moreover, owners of Japanese cars can often afford to buy a contract catalyst without mileage in the Russian Federation for relatively little money. Many craftsmen simply remove the catalyst and install a flame arrester (or an empty pipe altogether). Doing this is categorically undesirable for many reasons. Let's look at why it is better to replace the catalyst with another one:

For which cars is this relevant?

It is impossible to say that error P0420 is typical for a specific make or model of car. This is a common mistake.

Basically, error P0420 appears on cars whose mileage is more than 100 thousand kilometers.

In this case, the first error P0420 may appear closer to 100 thousand km. or it may appear when the engine has worked for over 300 thousand km.

Diagnostics of the control unit and error code P0420

If you look at the statistics of calls from motorists to service stations with such a problem as error P0420, you can identify several brands and models of cars that are susceptible to this problem. This may include:

• Ford Focus 2.
• Toyota Corolla.
• Kia Rio.
• Nissan Qashqai.
• Renault Logan
• Hyundai Solaris.
• UAZ Patriot.
• Opel Antara.
• Mazda 3.
• Suzuki Grand Vitara.
• Kia Ceed.
• Skoda Fabia
• Honda Accord, etc.

The ECU compares the values ​​of oxygen sensors on vehicles that meet the Euro-3 environmental standard and higher. Therefore, this error cannot appear on older cars.

It is important to take into account that error P0420 can equally affect both an expensive foreign car and an inexpensive domestic car.

Troubleshooting the catalyst and oxygen sensor

This is mainly a problem with budget models or cars that have traveled a significant number of kilometers. For them, error P0420 appears a little more often.

The lower the quality of the fuel used, the faster the ECU will encounter an error indicating low efficiency of the catalyst.

This is another reason to give preference to good quality fuel, use the services of trusted gas stations, and perform timely maintenance.

Advantages of replacing the catalyst:

• The planet will thank you. Those around you too.
• No need to bother with ECU (electronic control unit) firmware
• The problem will be solved once and for a long time. There is no interference with the vital components of the vehicle (ECU).

Disadvantages of replacing the catalyst:

• relatively expensive (but what is 5 - 10 thousand for your favorite car?)
• very expensive for some car models
• There may be difficulties with passing the annual technical inspection and also with selling the car

This is interesting: Oil filter puller - all types and options with your own hands: chain, belt, crab.
Changing the catalyst and removing it is up to you. Let's take a closer look at the pros and cons of removing the catalyst in order to be more objective.

Symptoms of the error

You probably won't have any symptoms other than the P0420 check engine light coming on. You may experience other engine problems that damage your catalytic converter.

This could include a rough (“rough”) idle, acceleration problems, misfires, or harsh gear changes. Always fix these problems first.

• The Check Engine light is on.
• Misfires.
• Rich mixture.
• Poor mixture.
• Engine oil is burning/gray-blue smoke coming from the exhaust pipe.
• Slow acceleration.

On which cars is this problem most common?

The problem with code P0420 can occur on different machines, but there are always statistics on which brands this error occurs more often. Here is a list of some of them:

• Acura (Acura MDX)
• Audi (Audi a4, Audi a6, Audi q5, Audi q7)
• BMW (BMW X5)
• Chery (Chery Tiggo)
• Cadillac (Cadillac SRX)
• Chevrolet (Chevrolet Aveo, Captiva, Cruz, Lanos, Lacetti, Spark, Trailblazer, Epica)
• Chrysler (Chrysler Voyager, Pacifica, PT Cruiser, Sebring, 300c)
• Citroen (Citroen C4, C5, Berlingo, Xara Picasso)
• Daewoo (Daewoo Gentra, Matiz, Nexia)
• Daihatsu
• Dodge (Dodge Caliber, Caravan, Stratus)
• Fiat (Fiat Doblo)
• Ford (Ford Galaxy, Maverick, Mondeo, Fiesta, Focus, Fusion, Explorer, C-Max)
• Geely (Geely MK, Emgrand)
• Honda (Honda Accord, Pilot SRV, Fit, Civic)
• Hover
• Hummer
• Hyundai (Hyundai Accent, Getz, Santa Fe, Solaris, Sonata, Elantra, i30, ix35, ix55)
• Infiniti (Infiniti fx35, qx56)
• Jaguar
• Jeep (Jeep Grand Cherokee, Compass, Liberty)
• Kia (Kia Karens, Magentis, Optima, Picanto, Rio, Sid, Sorento, Spectra, Sportage, Cerato)
• Lexus (Lexus gs300, gx470, ls430, lx470, rx300, rx330)
• Lifan (Lifan x60)
• Mazda (Mazda 3, Mazda 6)
• Mercedes (Mercedes w204)
• Mitsubishi (Mitsubishi Outlander, Lancer)
• Nissan (Nissan Almera, Qashqai, Micra, Murano, Note, Sentra, Patrol, Pathfinder, Primera, Teana, Tiida, X-Trail)
• Opel (Opel Antara, Astra, Vectra, Zafira, Insignia, Corsa, Meriva)
• Peugeot (Peugeot 107, 206, 207, 301, 307, 308, 406, 407, 408, 3008, Partner)
• Pontiac (Pontiac Vibe)
• Renault (Renault Duster, Kangu, Logan, Megan, Sandero, Scenic, Fluence)
• Saab
• Skoda (Skoda Octavia, Fabia)
• Subaru (Subaru Outback, Impreza, Legacy, Tribeca, Forester)
• Suzuki (Suzuki Grand Vitara, Ignis, Liana, Swift, sx4)
• Toyota (Toyota Avensis, Verso, Camry, Corolla, Land Cruiser, Matrix, Prado, Prius, Rav4, Celica, Highlander, Yaris)
• Volkswagen (Volkswagen Bora, Golf, Jetta, Caddy, Passat, Polo Sedan, Touareg, Tiguan)
• Volvo (Volvo s40, s60, s80, v40, xc70, xc90)
• Vortex (Vortex Tingo)
• Volga Cyber
• Gazelle Business
• Zaz Chance
• Lada Largus
• UAZ Bukhanka, Patriot, Hunter

You can sometimes encounter other errors with fault code P0420. The most common ones are: P0106, P0131, P0133, P0151, P0171, P0172, P0174, P0300, P0430, P0442, P0455, P0573, P069E.

Causes

The most common cause is the catalytic converter. It may simply be old and worn out. But there are many cases where the neutralizer is new, but at the same time it is a non-original part.

Some cheaper catalytic converters may not be efficient enough, and then you will have to buy an original catalytic converter.

Sometimes converters are installed too far back on the exhaust pipe. This will cause it to not get hot enough and cause a P0420 code.

• Damaged catalytic converter (most common cause).
• Non-original catalyst.
• Incorrect installation (placement) of the catalytic converter.
• Front oxygen sensor damaged / wiring fault.
• Rear oxygen sensor damaged / wiring fault.
• Exhaust gas leak.
• Leak on the intake manifold.
• Oil burns (damage to catalyst).
• Rich/lean mixture (damage to catalyst).
• Misfires (damage to catalyst).
• Faulty engine control unit (rare).

Causes

Error p0420 can also appear for many reasons. The operating conditions that most negatively affect the performance of the catalyst are:

• Use of low-quality fuel.
• Mechanical damage.
• Operating a car with a faulty ignition system (primarily with constant misfire in the cylinders).

They have a negative impact on the condition of the catalyst and the malfunction of other parts and elements. For example, malfunctions in the operation of this part can be observed if the oxygen sensor, manifold, or muffler are damaged. Burnout of gaskets in the exhaust system also has a negative impact on the performance of the catalytic converter and lowers the response threshold of the sensor that displays error p0420.

Once the causes of catalyst failure have been correctly identified, you can begin to eliminate them.

Trouble-shooting

These are just possible solutions and you should never change parts without proper diagnostics as you could be throwing money away if you are unlucky.

Read the entire article if you want to learn how to properly diagnose this trouble code just like an experienced auto mechanic would. It will take time and may require some skill, but you won't spend $1000 to replace a good catalytic converter.

• Replace the catalytic converter.
• Replace with original catalyst.
• Replace the front oxygen sensor.
• Replace the rear oxygen sensor.
• Repair of faulty electrical wiring.
• Correct oil burning.
• Correct misfire.
• Correct lean/rich mixture.
• Check the data using an OBD2 scanner.
• Replace the engine control unit (rarely).

Error Resolution Table

How severe is the catalyst efficiency error?

With this error, the driver does not experience problems driving a Ford . This code can be ignored. However, if you do not pay attention to this problem, serious damage can be caused to other parts of the car.

If the cause of the error is not corrected promptly, the catalytic converter may be seriously damaged. Since the catalytic converter is an expensive part, it is very important that the cause of the problem be repaired as soon as possible. If the catalyst is destroyed, its remains may enter the engine cylinders, which will result in a major overhaul of the Ford or replacement of the unit.

Causes of damage to the catalytic converter

There are several causes of catalytic converter damage that can trigger the P0420 code. Here are the most common ones.

• Misfires.
• Oil consumption.
• Leaks at the outlet.
• Inlet leaks.
• Rich mixture.
• Poor mixture.
• Malfunction of the ECM/PCM control unit.

There are many reasons that lead to malfunctioning oxygen sensors or catalytic converters. You should make sure to correct these problems before you replace any part. Otherwise, they may be damaged again. Check the controller DTC memory for any other trouble codes.

Fix them first. Make sure your car is not burning oil by checking the exhaust smoke, blue smoke = oil, white = water, gray/black = rich mixture.

Error P0420: description, what it causes, how to fix it

Problems that arise during the operation of the car indicate the presence of a malfunction in the functioning of certain of its units. In the operation of electrical and electronic systems, they appear in the form of an indicator on the dashboard “Check Engine”, which is popularly called simply “Check”.

The appearance of a “check” signals the car owner about the need to diagnose the car as soon as possible. If you have an ELM scanner, diagnostics can be carried out independently. To decipher the fault code of the car control unit, you must:

How to Diagnose Code P0420

Here is a guide on how a professional auto mechanic will diagnose a trouble code. This guide may require knowledge of vehicle electrical systems, and you may need some tools to complete the task.

But even if you have no idea about car electronics, you can still gain useful information.

You should always connect your car charger when troubleshooting your car. Low battery voltage can cause other unrelated error codes that will confuse you. Low voltage may damage the control unit or other electronics.

Connect the charger

Connect the charger to the battery and make sure it charges the battery correctly.

You should use a charger that provides at least 4 Amps while troubleshooting. A lower charging current may result in the battery being discharged when the ignition is turned on.

Connecting an OBD2 scanner

Connect an OBD2 scanner to read the P0420 code. You can use a diagnostic scanner or an ELM327 adapter with the Torque program.

3. Check for other fault codes

Check for other errors that may cause damage to the converter or any oxygen sensor errors. If there is an error in the lambda sensor, then replace or check it first, this may also fix the P0420 code.

Correct all other trouble codes before correcting the P0420 code.

Always write down any error code numbers, do not simply erase them.

Check for blue smoke while the engine is running

Increase the engine speed and check for gray-blue smoke from the exhaust pipe. Blue smoke = burning oil. Replacing the catalyst will not help. It will most likely fail again very quickly. Burning oil can also damage the oxygen sensors and cause them to read the mixture incorrectly.

You should always check for white, gray and black smoke. White smoke comes from water in the exhaust pipe, gray/black smoke comes from a rich mixture.

Check for exhaust leaks

Raise the vehicle while it is running. Listen and look for any exhaust leaks in front of the rear lambda probe. An exhaust leak can cause the O2 sensors to receive incorrect data and may trigger a fault.

If you have an exhaust leak behind the rear oxygen sensor, this should not cause an error.

Tips on how to find exhaust leaks:

Test drive

Take the car for a test drive and make sure there are no leaks or other symptoms. Drive fairly vigorously for some time so that the catalytic converter warms up. If skipping or other strange behavior appears, start diagnosing it first.

Drive to the garage and lift the car

Raise the car and keep it idling. Make sure you have proper ventilation. Connect an OBD2 scanner and check the current data from both O2 sensors.

Open the signal graph from oxygen sensors. Start the car engine and make sure that the temperature of the catalytic converter is at least 400 °C. You can use a digital laser thermometer to check the temperature.

Both charts should be open so you can see them.

The front sensor should constantly jump between 0 - 1 Volt, and the rear sensor should show a stable 0.7 - 0.9 Volt. This means everything is working properly.

If the catalytic converter is damaged or not hot enough, the rear lambda probe signal will fluctuate in the same way as the front one.

You can also use a digital multimeter. To do this, you need to check the voltage from the rear O2 sensor. But the signals are high speed and it can be difficult to read such voltages with a multimeter.

Check catalyst temperature

You can also check the temperature on the neutralizer. Make sure it is still hot before checking. Use a digital laser thermometer to measure.

Check the temperature just before, in the middle and after the catalyst. If you get the same temperature at all points when the neutralizer is hot (over 400 C°), then it is most likely empty or damaged.

If the catalytic converter is working correctly, the temperature should be 100-150 C° higher directly behind it than in front of it.

If the temperature in front of the catalyst is much higher, the car may be running rich and the converter is working too hard. This may also be due to the catalytic converter being blocked or having poor exhaust flow.

Video on how to check your catalytic converter using the Torque Pro app:

Summarize your results

Summarize the diagnostic results. If you have no other error codes, the front oxygen sensor signal changes, the catalytic converter temperature is uniform, and you do not see blue smoke, replace the catalytic converter.

Code P0420 can be a problem to diagnose correctly. If you have read this repair guide and received incorrect results, you can replace your catalytic converter with reasonable confidence.

If your diagnostic results look good but you still get a P0420 code, there is a small chance that the catalytic converter is still causing the fault.

In rare cases, you may have a faulty ECM.

If you find any gaps, gray-blue smoke or other problems, correct them and remove the error. With luck, the P0420 code may not return.

Error P0420 - what does it mean, symptoms, causes, diagnosis, solutionAre you trying to get rid of the P0420 error code? Then this article is for you. The P0420 fault can be difficult to diagnose. You think you have fixed the error, but after 100 km the Check Engine light comes on again. This code is triggered when the engine control module detects a faulty catalytic converter. It uses one oxygen sensor at the front of the exhaust manifold - before the catalyst, and another oxygen sensor - after the catalytic converter to measure the efficiency of the catalyst. In this article, you will learn everything you need to know about the P0420 code to fix it once and for all. Contents What does code P0420 mean? P0420 is triggered in the Electronic Control Unit (ECU) when there is a problem with the performance of the catalytic converter. The controller uses two oxygen sensors - one before and one after the catalyst to measure its efficiency. The error occurs if the converter or oxygen sensor malfunctions, which begins to transmit incorrect data. We receive many messages asking about the P0420 code. It keeps coming back after several repairs and you just end up spending more and more money on auto repair work. This trouble code may confuse you because there is a lot of misinformation about it. Catalytic Converter The front O2 sensor measures the air/fuel mixture. It tells the control unit if the engine is running rich or lean. The rear O2 sensor is the diagnostic oxygen sensor for this error code. If the rear oxygen sensor receives incorrect values, a P0420 fault will be stored in the ECU. This could be due to a faulty catalytic converter or one of the O2 sensors failing. There may also be many other problems with the engine that are destroying the catalytic converter, and if you install a new one, it may be damaged again. The oxygen sensor is also called a lambda probe. Many people think that a lean or rich mixture can cause this error code. Yes, it is possible, but not in the way you think. A rich or lean mixture can damage the catalytic converter and when it is damaged/full of fuel it will be low in efficiency and the rear oxygen sensor will see this and trigger a P0420 code. Symptoms of the Error You probably won't have any symptoms other than an illuminated Check Engine Light with code P0420. You may experience other engine problems that damage your catalytic converter. This could include a rough (“rough”) idle, acceleration problems, misfires, or harsh gear changes. Always fix these problems first. The Check Engine light is on. Misfires. Rich mixture. Poor mixture. Engine oil is burning/gray-blue smoke coming from the exhaust pipe. Slow acceleration. Causes The most common cause is the catalytic converter. It may simply be old and worn out. But there are many cases where the neutralizer is new, but at the same time it is a non-original part. Some cheaper catalytic converters may not be efficient enough, and then you will have to buy an original catalytic converter. Sometimes converters are installed too far back on the exhaust pipe. This will cause it to not get hot enough and cause a P0420 code. Damaged catalytic converter (most common cause). Non-original catalyst. Incorrect installation (placement) of the catalytic converter. Front oxygen sensor damaged / wiring fault. Rear oxygen sensor damaged / wiring fault. Exhaust gas leak. Leak on the intake manifold. Oil burns (damage to catalyst). Rich/lean mixture (damage to catalyst). Misfires (damage to catalyst). Faulty engine control unit (rare). Troubleshooting These are just possible solutions and you should never replace parts without proper diagnostics as you could be throwing money away if you are unlucky. Read the entire article if you want to learn how to properly diagnose this trouble code just like an experienced auto mechanic would. It will take time and may require some skill, but you won't spend $1000 to replace a good catalytic converter. Replace the catalytic converter. Replace with original catalyst. Replace the front oxygen sensor. Replace the rear oxygen sensor. Repair of faulty electrical wiring. Correct oil burning. Correct misfire. Correct lean/rich mixture. Check the data using an OBD2 scanner. Replace the engine control unit (rarely). Troubleshooting Chart Code Symptoms Causes Causes of Catalyst Damage Error P0420 Check Engine Misfire Rich Lean Burning Oil/Blue Smoke from Exhaust Pipe Slow Acceleration Faulty Catalyst Front O2 Sensor Rear O2 Sensor Exhaust Leak Oil Consumption Misfires/Lean Mixture Damaging Catalyst Misfires Ignition Oil Consumption Exhaust Leaks Intake Leaks Rich Composition Lean Composition ECU Malfunction Causes of Catalytic Converter Damage There are several causes of catalytic converter damage that can trigger the P0420 code. Here are the most common ones. Misfire. Oil consumption. Leaks at the outlet. Inlet leaks. Rich mixture. Poor mixture. Malfunction of the ECM/PCM control unit. There are many reasons that lead to malfunctioning oxygen sensors or catalytic converters. You should make sure to correct these problems before you replace any part. Otherwise, they may be damaged again. Check the controller DTC memory for any other trouble codes. Fix them first. Make sure your car is not burning oil by checking the exhaust smoke, blue smoke = oil, white = water, gray/black = rich mixture. How to Diagnose a P0420 Code Here is a guide on how a professional auto mechanic will diagnose the trouble code. This guide may require knowledge of vehicle electrical systems, and you may need some tools to complete the task. But even if you have no idea about car electronics, you can still gain useful information. You should always connect your car charger when troubleshooting your car. Low battery voltage can cause other unrelated error codes that will confuse you. Low voltage may damage the control unit or other electronics. 1. Connect the charger Connect the charger to the battery and make sure it charges the battery correctly. You should use a charger that provides at least 4 Amps while troubleshooting. A lower charging current may result in the battery being discharged when the ignition is turned on. 2. Connecting an OBD2 scanner Connect an OBD2 scanner to read the P0420 code. You can use a diagnostic scanner or an ELM327 adapter with the Torque program. 3. Check for other fault codes Check for other faults that could damage the converter or any oxygen sensor faults. If there is an error in the lambda probe, then replace or check it first, this may also fix the P0420 code. Correct all other trouble codes before correcting the P0420 code. Always write down any error code numbers, do not simply erase them. 4. Check for gray-blue smoke while the engine is running. Increase engine speed and check for gray-blue smoke from the exhaust pipe. Blue smoke = burning oil. Replacing the catalyst will not help. It will most likely fail again very quickly. Burning oil can also damage the oxygen sensors and cause them to read the mixture incorrectly. You should always check for white, gray and black smoke. White smoke comes from water in the exhaust pipe, gray/black smoke comes from a rich mixture. 5. Check for exhaust leaks Raise the vehicle while it is running. Listen and look for any exhaust leaks in front of the rear lambda probe. An exhaust leak can cause the O2 sensors to receive incorrect data and may trigger a fault. If you have an exhaust leak behind the rear oxygen sensor, this should not cause an error. Tips on how to find exhaust leaks: 6. Test Drive Take the car for a test drive and make sure there are no leaks or other symptoms. Drive fairly vigorously for some time so that the catalytic converter warms up. If skipping or other strange behavior appears, start diagnosing it first. 7. Drive to the garage and jack up the car. Raise the car and keep it idling. Make sure you have proper ventilation. Connect an OBD2 scanner and check the current data from both O2 sensors. Open the signal graph from oxygen sensors. Start the car engine and make sure that the temperature of the catalytic converter is at least 400 °C. You can use a digital laser thermometer to check the temperature. Both charts should be open so you can see them. The front sensor should constantly jump between 0 - 1 Volt, and the rear sensor should show a stable 0.7 - 0.9 Volt. This means everything is working properly. If the catalytic converter is damaged or not hot enough, the rear lambda probe signal will fluctuate in the same way as the front one. You can also use a digital multimeter. To do this, you need to check the voltage from the rear O2 sensor. But the signals are high speed and it can be difficult to read such voltages with a multimeter. 8. Check the temperature of the catalyst You can also check the temperature on the converter. Make sure it is still hot before checking. Use a digital laser thermometer to measure. Check the temperature just before, in the middle and after the catalyst. If you get the same temperature at all points when the neutralizer is hot (over 400 C°), then it is most likely empty or damaged. If the catalytic converter is working correctly, the temperature should be 100-150 C° higher directly behind it than in front of it. If the temperature in front of the catalyst is much higher, the car may be running rich and the converter is working too hard. This may also be due to the catalytic converter being blocked or having poor exhaust flow. Video on how to test your catalytic converter using the Torque Pro app: 9. Summarize your results Summarize your diagnostic results. If you have no other error codes, the front oxygen sensor signal changes, the catalytic converter temperature is uniform, and you do not see blue smoke, replace the catalytic converter. Code P0420 can be a problem to diagnose correctly. If you have read this repair guide and received incorrect results, you can replace your catalytic converter with reasonable confidence. If your diagnostic results look good but you still get a P0420 code, there is a small chance that the catalytic converter is still causing the fault. In rare cases, you may have a faulty ECM. If you find any gaps, gray-blue smoke or other problems, correct them and remove the error. With luck, the P0420 code may not return. What are the causes of oil leakage? If you see blue smoke coming from the muffler and you have a P0420 code, you need to fix the oil leak first. But how to do this, you ask? Internal oil leaks can often be costly. Sometimes complete disassembly of the engine is required, but in some cases this may be the cause of the error. We will describe the most common causes of internal oil leakage. The best way to find the problem is to check the compression to see if there is any pressure loss in the cylinders due to the piston rings. Clogged PCV System (Most Common) A clogged PCV system is the most obvious cause of blue smoke. You can start by unscrewing the oil cap while the engine is running. The cap should be sucked back in because most engines have a vacuum if everything is working properly. If you feel excess pressure in the crankcase, the first thing you should check is the crankcase ventilation. There are often 1-3 hoses running from the crankcase to the air filter housing. Check them and make sure the tubes are not clogged. A clogged crankcase vent can cause oil to be forced past the piston rings and valve guides. Turbine Wear Another common problem if your car is turbocharged is oil leaking, which is sucked into the engine and burned there. How to find out? You need to check the presence of oil in the intercooler (intermediate air cooling radiator). In this case, your turbocharger may be worn out. You can also remove the charge tubes and check the turbocharger impeller to make sure it feels good and isn't loose. The clearance should be ~1mm on the sides, depending on whether the turbine is ball bearing or not. Worn valve guides Worn valve guides and seats can cause oil to burn. However, this is not an easy fault to diagnose or repair. Always check the piston rings for leaks before replacing them. The easiest way to replace the valve guides is to lift the cylinder head and remove the valve springs. There are tools that can be used to increase the pressure inside the cylinder and replace the liners without removing the head, but the procedure is not simple, we recommend having a qualified mechanic do this for you. Worn/Damaged Piston Rings Worn or damaged piston rings are a fairly common problem when it comes to internal oil leaks. Most often this can be checked by measuring the compression. You can inspect the pistons with an endoscope in the form of a small camera through the spark plug holes. If you find that the piston rings are damaged, the only way to fix this is to disassemble the entire engine and remove the pistons from the block. If you are installing new piston rings, be sure to check the pistons and piston ring clearance. Cracks in the cylinder head Cracks in the cylinder head or engine block are also a possible cause of oil combustion. However, this problem is not very common, but it is possible. If you find cracks, you will have to contact a specialist who will weld them, if possible. In many cases, the entire cylinder head or cylinder block will have to be replaced. It is not always possible to weld cracks. How does a catalytic converter work? Here is a video of how a catalytic converter works: The picture shows the parts of a catalytic converter. The catalyst is used to purify exhaust gases. If you look at it, you will see that it looks like a honeycomb in a beehive. Engine exhaust produces hydrocarbons (unburnt fuel), carbon monoxide (from combustion in the engine), and nitrogen oxides (formed when heat in the engine causes nitrogen in the air to combine with oxygen). The catalytic converter contains platinum and palladium (which is why you get paid for the used catalyst). The ceramic structure converts carbon monoxide (carbon monoxide CO) into carbon dioxide (carbon dioxide CO2). It also converts hydrocarbons into water and carbon dioxide. Nitric oxide is converted back to oxygen and nitrogen. If the conversion fails, the rear oxygen sensor will sense this and send a signal to the control unit, which will activate the P0420 code. How does an oxygen sensor work? Video of how the lambda probe works: What is the function of the front oxygen sensor? Oxygen Sensor The front O2 sensor is adjustable. It will measure the mixture of exhaust gases that pass through it. Using this data, the ECU determines whether the mixture is rich or lean. The front oxygen sensor can be installed either directly in front of the catalytic converter or on the exhaust manifold. Some vehicles use multiple front O2 sensors for different cylinders. There are two types of oxygen sensors: narrowband sensor (most common) wideband sensor (newer vehicles). A wideband sensor reads the signal much faster. Narrowband usually uses four wires. One is the power supply, one is the signal and two wires are for heating. You can simply determine whether you have a narrowband or wideband sensor. Look at the number of wires. A broadband sensor will have 5 or more wires, and a narrow-band-2-4 wires. If the front sensor O2 is faulty, then the ECU thinks that the engine works on a rich mixture, while it works on the poor in fact. This can cause an error P0420. What is the function of the rear oxygen sensor? The rear lambda-zond does not differ in the structure from the front. The difference is that the rear sensor does not provide any information for adjusting the mixture to the engine control unit. The purpose of the rear sensor O2 is only to check whether the catalytic neutralizer works correctly. If the rear sensor feels that the catalyst is working incorrectly, it will send this information to the control unit, which will launch and save the P0420 malfunction code. What does Bank 1, Bank 2 mean? The designation Bank 1 and Bank 2 is usually used if the car has more than four cylinders. But it is also used on four -cylinder engines. This means that you probably have two exhaust pipes or that the engine cylinders are divided into several O2 sensors. "Bank" means which side or on which exhaust pipe the sensor is located. Bank 1 is always installed on cylinders 1-3-5-7-9, etc. The Bank 2 sensor controls the cylinders 2-4-6-8-10. You can turn off one oxygen sensor and consider errors by the OBD2 scanner. This will find out where the sensor is installed-in Bank 1 or Bank 2. Is it possible to remove any detail to get rid of the P0420 code? You cannot just remove any details to fix the P0420. This will most likely provoke another error or other malfunctions. You can reprogram the control unit to remove the control of the catalytic neutralizer. But this is not recommended, because in most countries there is a law according to which the catalyst should work. If you reprogram the controller, you can also remove the catalytic neutralizer. Remember that if you remove the catalyst, then most likely you will not pass the inspection for the number of emissions into the atmosphere. There is another way to deceive the ECU-to replace the rear lambda zond. This method is for those who want to get rid of the P0420 error by any methods. We don't recommend doing this. Here you can see the prices and types of deceit of the oxygen sensor. How can the burned oil damage the catalyst? If there is an internal leak of oil in the engine that burns in the cylinders, it will go through the exhaust pipe. This creates blue smoke that we mentioned earlier. The oil stuck and burns in the neutralizer, damaging it. The catalyst temperature can reach more than 600 C °. And if it overheats, it is damaged. Then, if you replace the catalytic neutralizer without eliminating oil leakage, the oil will continue to get stuck and burn in it. Thus, you will also damage your new catalyst. How can a rich or poor mixture cause an error P0420? A rich or poor fuel mixture can damage your neutralizer in several ways. Due to the rich mixture, too much fuel will fall into the catalyst. It will ignite and destroy it. The poor mixture can cause a high temperature of exhaust gases. It can also damage the catalytic neutralizer. However, the catalyst is not damaged quickly due to this kind of problem. But in the long run, it wears out much faster than if the fuel mixture was correct. How can the passes cause an error P0420? Ignition misses are a common cause of damage to catalytic neutralizers. This is because during ignition passes, unbroken fuel appears, which enters the neutralizer through the exhaust manifold. Since it is hot, fuel is ignited and causes a reverse reaction. These ignitions are fatal for any catalytic neutralizer and can quickly damage it. Another option lies in the fact that unsecured fuel comes out, and immediately after that there is fire from another cylinder, which ignites the mixture, and it explodes inside the exhaust pipe. These explosions can quickly damage the catalyst. Tools for eliminating the P0420 error to correct this malfunction code, you may need several tools to make diagnostics much easier and better. OBD2 scanner is necessary to diagnose an error code for viewing data in real time, etc. We recommend lending or buying a diagnostic scanner that can show signals in the graphs to facilitate the diagnosis. You should always have a car charger when you diagnose a car. The low voltage of the battery can cause other errors that will lead to incorrect conclusions. Low voltage can also damage control units or other electronics, if you are not very lucky. The digital laser thermometer is necessary to check the temperature of the catalytic neutralizer. The temperature issued by the OBD2 scanner is calculated, not real. The thermometer is also useful for many other tasks when you repair the car. Ideal for eliminating the malfunctions of the cooling system. A digital multimeter is required for any electrical measurements and is absolutely necessary. You will need a multimeter to search for almost all electronics malfunctions. He is not so dear. Buy a multimeter depending on your needs - there are both very cheap and expensive. The deceit of the oxygen sensor can be used in order to deceive the control unit, and this can correct the error P0420. This is a non -recommended method. If you think that your catalytic neutralizer is contaminated or there is oil from earlier internal oil leaks, you can try to use the catalyst cleaner. It is also used for other tasks when cleaning the exhaust system. The known reasons for the error P0420 by car models in some cars P0420 error are better known than in others. Here is a list of the most common reasons for each brand. These cars, as you know, have problems with the P0420 error. Remember that these are only general recommendations, and you must make the correct diagnosis before changing any details. Toyota Corolla The most common cause of the P0420 error on Toyota Corolla is a catalyst malfunction. But, this can often be caused by oil passing through the piston rings, which stuck in a catalytic neutralizer. First, check the presence of leaks on the inlet and release. Then check if there is a gray -haired smoke from the exhaust pipe. If you see him, then this is an occasion to contact a car service to find the oil comes from. The standard reason may be the crankcase ventilation. If you do not see blue smoke at any engine speed, most likely your catalytic neutralizer is worn out. Ford Focus Ford focus usually has an air leak. It can also be any broken solenoid that causes an incorrect fuel-air mixture, activating the error. Check the controller’s memory using a diagnostic scanner to count errors associated with the air-fuel mixture. If everything looks normal, check the presence of exhaust gas leaks. Replace the catalytic neutralizer if you cannot find any malfunctions or other mixture problems. Subaru / Subaru Forester Subaru usually has the same problem as Toyota Corolla. Check the presence of air leaks or other malfunctions associated with the fuel mixture. Check the presence of exhaust gas leaks in front of a catalytic neutralizer. The most common problem on Subaru engines is the catalyst itself. Volkswagen (VW) / Skoda / Seat / Audi A4 1.8 T / V6 2.4 These VAG cars have some well -known malfunctions that cause the P0420 code. Check the work valves at the inlet. Make sure that the crankcase ventilation is not contaminated, as a result of which the engine burns the oil that clogs the catalytic neutralizer. Check the presence of exhaust gas leaks around any folds on the exhaust pipe (general reason). Check the presence of any codes of malfunctions O2. If no problems are found, replace the neutralizer. This is a very common problem both at 1.8 T and on V6 gasoline engines. The 1.8 T catalyst can be quite difficult to replace if you have no experience in this. V6 has two catalytic neutralizers, so make sure that you eliminate problems and replace the catalyst on the right side. The conclusion in most cases the catalytic neutralizer is faulty and this is evidenced by the error code P0420. But there may be other reasons why the catalyst was damaged. Always correct all other fault codes before eliminating P0420. You can use special tools or reprogram control unit to deceive it. This will help get rid of the P0420 error. Bank 1, Bank 2 (Bank 1, Bank 2) indicate which of the O2 sensors or which catalytic neutralizer is faulty. The catalytic neutralizer cleans the exhaust gases and its removal is illegal.

What are the causes of oil leakage?

If you see blue smoke coming from the muffler and you have a P0420 code, you need to fix the oil leak first. But how to do this, you ask?

Internal oil leaks can often be costly. Sometimes complete disassembly of the engine is required, but in some cases this may be the cause of the error.

We will describe the most common causes of internal oil leakage. The best way to find the problem is to check the compression to see if there is any pressure loss in the cylinders due to the piston rings.

Clogged crankcase ventilation system (most common)

A clogged crankcase ventilation system is the most obvious cause of blue smoke. You can start by unscrewing the oil cap while the engine is running. The cap should be sucked back in because most engines have a vacuum if everything is working properly.

If you feel excess pressure in the crankcase, the first thing you should check is the crankcase ventilation. There are often 1-3 hoses running from the crankcase to the air filter housing. Check them and make sure the tubes are not clogged. A clogged crankcase vent can cause oil to be forced past the piston rings and valve guides.

Turbine wear

Another common problem if your car is turbocharged is oil leaking, which is sucked into the engine and burned there. How to find out? You need to check the presence of oil in the intercooler (intermediate air cooling radiator). In this case, your turbocharger may be worn out.

You can also remove the charge tubes and check the turbocharger impeller to make sure it feels good and isn't loose. The clearance should be ~1mm on the sides, depending on whether the turbine is ball bearing or not.

Worn valve guides

Worn valve guides and seats can cause oil to burn. However, this is not an easy fault to diagnose or repair. Always check the piston rings for leaks before replacing them. The easiest way to replace the valve guides is to lift the cylinder head and remove the valve springs.

There are tools that can be used to increase the pressure inside the cylinder and replace the liners without removing the head, but the procedure is not simple, we recommend having a qualified mechanic do this for you.

Worn/damaged piston rings

Worn or damaged piston rings are a fairly common problem when it comes to internal oil leaks. Most often this can be checked by measuring the compression. You can inspect the pistons with an endoscope in the form of a small camera through the spark plug holes.

If you find that the piston rings are damaged, the only way to fix this is to disassemble the entire engine and remove the pistons from the block.

If you are installing new piston rings, be sure to check the pistons and piston ring clearance.

Cracks in the cylinder head

Cracks in the cylinder head or engine block are also a possible cause of oil burning. However, this problem is not very common, but it is possible.

If you find cracks, you will have to contact a specialist who will weld them, if possible. In many cases, the entire cylinder head or cylinder block will have to be replaced. It is not always possible to weld cracks.

Solving the problem of low catalyst efficiency

Often the problem of a catalyst with poor efficiency is solved by flashing the ECM. You just install different software, where the toxicity standard is different (for example, EURO2). The system still compares the value from the two sensors, but now the difference in parameters will correspond to EURO2 toxicity. What can this achieve? At a minimum, the error on the dashboard will disappear, but nothing more.

This is interesting: Why spark plugs wear out and whether they need to be changed at all - signs of malfunctions and the main reasons

Catalyst replacement

The most expensive option is to replace the old catalyst with a new and original one. However, this is an expensive procedure due to the high cost of the device itself. The price can reach 40 thousand rubles.

A cheaper option is to use a universal catalyst, which has a lower operating efficiency compared to the original one (it’s all about the material: the original catalyst is ceramic, and the universal one is made of metal). Also, its service life is only 30-50 thousand kilometers, and not all cars accept it well. But there is no need for any software changes in the system. And another option: during disassembly you can find the original catalyst, albeit a used one. It will be unknown what its mileage is and how soon it will fail.

Installing a flame arrester

If toxicity standards don’t bother you at all, then a cheap and simple option is to install a flame arrester. To do this, the catalyst can is cut out and the second lambda blende is installed. This is called hardware deception, but there is also software deception. We are talking about reflashing the system and transferring it to a lower toxicity standard. It is worth noting that this solution to the problem, although it involves more severe air pollution on the street, greatly increases engine power. After all, all these toxicity standards and compliance with environmental standards reduce the capabilities of the engine.

Removing the catalyst from the system

Alternatively, the catalyst can be completely removed from the exhaust system and a two-channel emulator can be installed, with which you can adjust the signal speed and response time.

It may also be that during the diagnostic process it turns out that the throughput of the catalyst is normal (about 0.21 kg/cm2 at 2000 rpm). This is quite possible, because the error is triggered even if the catalyst operates at 70% of its power. In this case, you can put a special spacer under the lambda probe. This is a very cheap solution, but it cannot be said that it is a panacea.

How does a catalytic converter work?

Here's a video of how a catalytic converter works:

The picture shows the parts of the catalytic converter. The catalyst is used to purify exhaust gases. If you look at it, you will see that it looks like a honeycomb in a beehive.

Engine exhaust produces hydrocarbons (unburnt fuel), carbon monoxide (from combustion in the engine), and nitrogen oxides (formed when heat in the engine causes nitrogen in the air to combine with oxygen).

The catalytic converter contains platinum and palladium (which is why you get paid for the used catalyst). The ceramic structure converts carbon monoxide (carbon monoxide CO) into carbon dioxide (carbon dioxide CO2). It also converts hydrocarbons into water and carbon dioxide. Nitric oxide is converted back to oxygen and nitrogen.

If the conversion fails, the rear oxygen sensor will sense this and send a signal to the control unit, which will activate the P0420 code.

What does it indicate?

The occurrence of error P0420 makes it clear to the car owner that not everything is in order with the operation of the catalyst and it is not able to cope with the entire volume of incoming exhaust gases. However, this does not always mean that the catalyst has failed. It is likely that it became clogged and this, in turn, negatively affected the throughput.

It is important to note that if there are two neutralizers on one car, this error code is P0430. This is typical for vehicles of Euro 3 standard from above.

What is the function of the front oxygen sensor?

Oxygen Sensor
The front O2 sensor is adjustable. It will measure the mixture of exhaust gases that pass through it. Using this data, the ECU determines whether the mixture is rich or lean.

The front oxygen sensor can be installed either directly in front of the catalytic converter or on the exhaust manifold.

Some vehicles use multiple front O2 sensors for different cylinders.

There are two types of oxygen sensors:

• narrowband sensor (most common)
• wideband sensor (new vehicles).

A wideband sensor reads the signal much faster.

Narrowband usually uses four wires. One is the power supply, one is the signal and two wires are for heating. You can simply determine whether you have a narrowband or wideband sensor. Look at the number of wires.

A wideband sensor will have 5 or more wires, while a narrowband sensor will have 2-4 wires.

If the front O2 sensor is faulty, the ECU thinks the engine is running rich when it is actually running lean. This may cause the P0420 code.

Chip tuning of Skoda cars in Tula - Intercar

Skoda Octavia 2022. The car is still under warranty. The transmission is automatic and the mileage is only 30,000 km. Although the power is 110 hp. With. it still felt like the car was “suffocated.” Unfortunately, the more modern the car, the more it is limited by environmental standards for reducing exhaust toxicity. The same can be said about the “inhibited” [...]

A 2013 Skoda Octavia with a 1.8 turbo engine and a classic automatic transmission (not DSG) came to remove the catalyst. Mileage 286,000 km, diagnostics showed error P0420 (catalyst efficiency). It is also recommended to replace the timing chain. In addition to all this, there is oil consumption. We do the firmware for Euro2, naturally we don’t miss the opportunity to improve the dynamics [...]

We do chip tuning for a Skoda Yeti with a 1.8 turbo engine, produced in 2022, with a DSG6 gearbox. Mileage 18000 km. The car is under warranty. There are no diagnostic errors. There is no need to remove the catalyst. The process of preparing a car for chip tuning. We identify the control unit. In our case, the car is equipped with a Bosch Med17.5 control unit number […]

We do chip tuning for a Skoda Octavia with a 1.8 turbo engine, produced in 2013, with a manual transmission. Mileage 66000 km. There are no diagnostic errors. There is no need to remove the catalyst. The process of preparing a car for chip tuning. We identify the control unit. In our case, the car is equipped with a Bosch Med17.5 control unit number 3T0907115F. Firmware version […]

Chip tuning Skoda Octavia A5 1.4 Turbo Turbocharged 1.4 engine with a capacity of 122 horsepower. Engine letter designation CAXA. 7-speed DSG gearbox. The mileage is currently 192,000 km, there is an error on the catalyst with code P0420. The catalyst has long been cut out. The potential of this engine is quite large! Many are sure that 1.4 works […]

Chip tuning Skoda Octavia 2014 1.6 110l. With. The car has already covered more than 100 thousand kilometers, so its owner decided to remove the catalyst. There were no errors, the car worked well overall, but there was a slight decrease in traction... We start with identifying the engine control unit Installed ECU Bosch ME17.5.26 04E907309AH Engine letter CWVA Firmware version: […]

Chip tuning and EGR removal for Skoda Superb 2.0Tdi Skoda Superb 2.0 liter diesel car. Engine power 140 horsepower, 6-speed DSG gearbox. An EGR error appeared while the car was driving on the highway. The traction became significantly worse, the engine went into emergency operation. The cost of repairing the recirculation system [...]

Chip tuning Skoda Fabia 1.6 AT Skoda Fabia with 1.6 engine (CFNA) and automatic transmission, produced in 2012. The catalyst was destroyed and the engine stopped starting. After the catalyst was cut out, the “check engine” light came on and an error appeared regarding the low efficiency of the catalyst. The car was brought to us for high-quality chip tuning for Euro2. […]

Skoda Superb 2012 car with a 1.8 petrol turbocharged engine (152 horsepower). Six-speed automatic transmission.

The task was to increase engine power and at the same time solve several problems, such as an error in the fuel adsorber, catalyst, swirl flaps of the intake manifold Reading the firmware identifiers Now we are working through the diagnostic connector, previously these […]

Tsi engine, 125 horsepower. The car is still under warranty. The dynamics are good, but we can do even better! First we diagnose the engine, there are no errors. Then we get the native firmware of the ECU 04E907309BH Bosch Med17.5.25 We write the firmware via the diagnostic connector, it takes about 40 minutes to calibrate the program. The output is 160 horsepower and absolutely […]

Today we will talk about how to turn a 90-horsepower Rapid into a 120-horsepower one. Chip tuning will be performed on the 2018 Skoda Rapid FL 1.6. Engine CWVB 90 horses. First, we read the native firmware, then we work on it for about 40 minutes. Then we write back through the diagnostic connector The block does not open, the car is new [...]

What is the function of the rear oxygen sensor?

The rear lambda probe does not differ in structure from the front one. The difference is that the rear sensor does not provide any information for adjusting the mixture to the engine control unit.

The purpose of the rear O2 sensor is only to check if the catalytic converter is working properly. If the rear sensor senses that the catalytic converter is not working properly, it will send this information to the control unit, which will trigger and store a P0420 trouble code.

How the car behaves (signs of error p0420)

Depending on which of the two variants of a catalyst malfunction occurs (clogged or destruction has begun), the car will exhibit their characteristic symptoms. In addition to the fact that the check engine light will light up on the instrument panel, and in some cars the catalyst overheating lamp will light up, the exhaust gases will no longer meet EURO 3-5 standards. In general, the signs that will trigger the P0420 (P0430) error may be:

Location of catalyst and oxygen sensors

• increased fuel consumption;
• decreased engine dynamics;
• changes in the smell of exhaust gases (became very unpleasant);
• rattling noise from the catalytic converter (if it crumbles);
• sometimes unstable idle;
• It may be difficult to start the engine. So, if you observe more than two of these signs at the same time, most likely the car has problems with the catalyst, and you cannot do without diagnostics to accurately find out the fault code!

What does Bank 1, Bank 2 mean?

The designation Bank 1 and Bank 2 is usually used if the vehicle has more than four cylinders. But it is also used on four-cylinder engines.

This means that you probably have two exhaust pipes or that the engine cylinders are split into multiple O2 sensors. “Bank” indicates which side or exhaust pipe the sensor is located on.

Bank 1 is always installed on cylinders 1-3-5-7-9, etc. Bank 2 sensor monitors cylinders 2-4-6-8-10.

You can disable one oxygen sensor and read errors with the OBD2 scanner. This will allow you to find out where the sensor is installed - in Bank 1 or Bank 2.

Is there any part that can be removed to clear the P0420 code?

You can't just remove some parts to fix P0420. This will most likely trigger another error or other malfunctions.

You can reprogram the control unit to remove the catalytic converter monitoring. But this is not recommended because in most countries there is a law that the catalyst must work.

If you reprogram the controller, you may also be able to remove the catalytic converter.

Remember that if you remove the catalytic converter, you will most likely fail the emissions test.

There is another way to fool the ECU - replacing the rear lambda probe. This method is for those who want to get rid of error P0420 by any means. We don't recommend doing this. Here you can see prices and types of oxygen sensor decoys.

Test methods and problem solving

In some cases, it is necessary to check the serviceability of the oxygen sensor or the exhaust system and manifold for leaks. Leaks and leaks can affect the operation of the O2 sensors and cause the P0420 error code to appear, but still, more often this problem is directly related only to the condition of the catalyst.

Some tips for a troubleshooting plan

Before starting diagnostics, in order to save time on finding out the cause and fixing the problem, we advise you to carry out a few simple checks, and then proceed to further, complex solutions to the problem. So:

1. First of all, remember what gas station you refueled at and whether you filled it with fuel, as always. And also make sure that there are no symptoms of coolant getting into the engine, as well as oil consumption.
2. Check the ignition timing. Reducing the ignition timing below the required angle can increase the temperature of the exhaust gases and, over time, reduce the efficiency of the catalyst.
3. Check the connector of the 2nd (“rear”) oxygen sensor. Having made sure that all this was unchanged, you will have to connect a computer to retrieve data from the electronic control unit.

Checking the operation of the catalytic converter and its parameters

To assess the efficiency of the catalyst, it is necessary to compare the output voltage graphs between the “upper” and “lower” oxygen sensors, as well as look at the fuel supply adjustment data.

Oxygen sensor readings on an oscilloscope

The output voltage of the oxygen sensor, read by the car's computer, will decrease when the mixture is lean and increase when it is rich. A normal reading for an oxygen sensor will fluctuate between 900 millivolts (rich condition) and 100 millivolts (lean condition).

Short-term adjustment, ideally, should tend to “0”, but on an engine with mileage, deviations from the norm of up to 10% are acceptable. And when the fuel adjustment exceeds 25%, then a long-term adjustment also occurs, so if both values ​​are present, this indicates a problem in preparing the fuel-air mixture. Therefore, pay attention to the presence of additional fault codes.

How to troubleshoot P0420

Some car owners, unaware of the origin of the P0420 error, may begin to eliminate the problem by cleaning the damper or replacing sensors that affect air and fuel consumption. While, if you need to try to replace something, it’s this:

Firstly, swap the lambda probes, upper and lower, since they are the same and can replace each other. Therefore, if the problem is precisely the non-working second oxygen sensor, then the error code will change (alternatively, error P0134 may appear).

Secondly, fill up with other gasoline, of better quality, and drive a little (if it’s because of the fuel, then a couple of days will change the situation).

The third step towards troubleshooting can be checking the catalyst, or rather, its throughput (there are several methods). Internal catalyst failure usually occurs due to abnormal operation of the engine systems upstream of the catalyst. An increased operating temperature of the converter is usually the cause of both the appearance of this code and its failure. For example, misfires can lead to elevated catalyst operating temperatures.

How can burnt oil damage the catalytic converter?

If there is an internal leak in the engine oil that is burned in the cylinders, it will exit through the exhaust pipe. This creates the blue smoke that we mentioned earlier. The oil gets stuck and burns in the converter, damaging it.

The catalyst temperature can reach more than 600 C°. And if it overheats, it is damaged. Then, if you replace the catalytic converter without fixing the oil leak, the oil will continue to get stuck and burn in it. This way you will also damage your new catalytic converter.

How can a rich or lean mixture cause P0420?

A rich or lean fuel mixture can damage your converter in several ways. A rich mixture will cause too much fuel to enter the catalyst. It will ignite and destroy him. A lean mixture can cause high exhaust gas temperatures. It can also damage the catalytic converter.

However, the catalyst is not damaged quickly due to this kind of problem. But in the long run, it wears out much faster than if the air/fuel mixture were correct.

Error P2187

The interpretation of error P2187 is as follows: the mixture in the system is too lean in idle mode. Often caused by a dirty mass air flow sensor, a clogged fuel filter, or air leaks in the manifold. Initially, you need to check the manifold, then the fuel filter and the mass air flow sensor itself. As practice shows, in most cases, Hyundai Solaris owners eliminate P2187 by cleaning or replacing the sensor itself.

How to check the sensor? There are several proven methods:

1. Disconnect all MAF connectors and start the engine. The controller switches to emergency operation mode, preparing the mixture only according to the remote control position. We drive in this mode for several hundred meters, if you feel a surge of previously lost power from the power unit, then the problem lies precisely in the mass air flow sensor.
2. Measure the voltage at the sensor outputs with a multimeter.

Problems associated with this sensor are quite common and annoying. The driver may be left without a car for some time. A new copy of the mass air flow sensor on the Hyundai Solaris is not cheap, but it is better to do all the work once, and then enjoy the quiet operation of the car. But you can try to clean the faulty mechanism using special cleaning agents, for example, carburetor cleaner. In some cases, due to such manipulation, the service life of the device can be extended.

How can omissions cause P0420?

Misfires are a common cause of damage to catalytic converters. This happens because during a misfire, unburned fuel appears and enters the converter through the exhaust manifold. Because it is hot, the fuel ignites and causes a backlash.

These fires are fatal to any catalytic converter and can quickly damage it. Another possibility is that the unburned fuel comes out and is immediately followed by a fire from another cylinder which ignites the mixture and it explodes inside the exhaust pipe. These explosions can quickly damage the catalyst.

Conditions for generating DTC P0420

The ECM, in the process of monitoring, compares the signals of the 1st and 2nd sensors during a given time interval, calculating the duration of the voltage signal, and if it goes beyond a given threshold, the “brain” of the car interprets this as a malfunction of the neutralizer. The threshold value of the difference between the amplitudes of the front S1 (taken as the standard) and rear S2 oxygen sensors is more than 0.7 times per minute. But the check light, indicating that an error has been recorded in the memory of the ECM unit, does not light up instantly, but only when a decrease in the performance characteristics of the catalytic converter occurs for 100 seconds, and the engine load should be from 21 to 63% when the crankshaft rotates 1,720 - 2,800 rpm, and the catalyst temperature exceeds 500 degrees.

Signal from oxygen sensor

During normal operation of the catalytic converter, the downstream heated oxygen sensor signal switches slowly between rich and lean conditions. Frequent switching of the lambda probe between these states indicates a decrease in the efficiency of the converter. As a result, its ability to accumulate oxygen is reduced.

The task of the catalyst is to oxidize carbon monoxide and neutralize CO2 hydrocarbon emissions in order to reduce the concentration of harmful substances. This process, starting with the Euro 3 standard, is monitored by two oxygen sensors. There is a constant comparison of the signals of the first and second lambda in order to register the convergence of their readings. Therefore, error code P0420, in due time, will bother all owners of cars, including VAZ, Nissan, Toyota, Chevrolet, Ford, Honda or others produced after 1996 and having 2 lambda probes in the exhaust system.

Tools to troubleshoot P0420

To fix this trouble code, you may need a few tools to make the diagnosis much easier and better.

• OBD2 scanner - essential for diagnosing error codes, viewing real-time data, etc. We recommend borrowing or purchasing a diagnostic scanner that can show signals in graphs to make diagnosis easier.
• You should always have a car charger when diagnosing your car. Low battery voltage can cause other errors that will lead to incorrect outputs. Low voltage can also damage control units or other electronics if you're really unlucky.
• A digital laser thermometer is required to check the temperature of the catalytic converter. The temperature value produced by the OBD2 scanner is calculated and not real. The thermometer is also useful for many other tasks when you are working on your car. Ideal for troubleshooting cooling system problems.
• A digital multimeter is required for any electrical measurements and is absolutely essential. You will need a multimeter to troubleshoot almost all electronics problems. It's not that expensive. Buy a multimeter depending on your needs - there are some very cheap ones and some expensive ones.
• Oxygen sensor spoofing can be used to fool the control unit and this may correct the P0420 code. This is not a recommended method.
• If you think your catalytic converter is dirty or has oil in it from earlier internal oil leaks, you can try using a catalyst cleaner. It is also used for other tasks when cleaning the exhaust system.

Symptoms

If an error code with the value P0420 is registered in the ECU, this can be guessed not only by scanning the control unit and connecting it with a scanner.

Most often, suspicions about a faulty catalyst arise from indirect signs. Yes, they can indicate other possible problems.

Since error P0420 appears not only in a situation where the catalyst fails, the symptoms can be quite varied. Namely:

• the engine does not work as well as before;
• dynamics decreases;
• at idle the engine behaves unstable;
• engine starting becomes more difficult;
• fuel consumption increases noticeably without increasing the load;
• during movement, a cracking sound occurs on the side of the catalyst;
• the exhaust gas changes its composition and color may change;
• the smell from the exhaust becomes more pronounced and unpleasant, sometimes sharp;
• The warning light on the dashboard, known to everyone as the Check Engine, comes on.

The majority of signs, apart from the crackling sound from the catalyst itself, potentially indicate various problems. But the manifestation of any of the symptoms discussed is a good reason to engage in diagnostics, find out the causes and try to troubleshoot.

Known Causes of P0420 by Vehicle Model

Some vehicles are more familiar with the P0420 code than others. Here is a list of the most common reasons for each brand. These vehicles are known to have problems with the P0420 code. Please remember that these are general guidelines only and you must make a proper diagnosis before changing any parts.

Toyota Corolla

The most common cause of the P0420 code on the Toyota Corolla is a faulty catalytic converter. But, this can often be caused by oil passing through the piston rings getting stuck in the catalytic converter.

First check for leaks at the inlet and outlet. Then check to see if there is gray blue smoke coming from the exhaust pipe. If you see it, then this is a reason to contact a car service to find where the oil comes from. The usual cause may be crankcase ventilation.

If you don't see blue smoke at any engine speed, your catalytic converter is likely worn out.

Ford Focus

Ford Focus usually has an air leak. It could also be any broken solenoid that is causing the fuel/air mixture to be incorrect, activating the fault.

Check the controller memory using a diagnostic scanner to read errors related to the air-fuel mixture. If everything looks normal, check for exhaust leaks.

Replace the catalytic converter if you cannot find any trouble codes or other problems with the mixture.

Subaru / Subaru Forester

Subaru usually has the same problem as Toyota Corolla. Check for air leaks or other fuel mixture related trouble codes.

Check for exhaust leaks in front of the catalytic converter. The most common problem with Subaru engines is the catalyst itself.

Volkswagen (VW) / Skoda / Seat / Audi A4 1.8 T / V6 2.4

These VAG vehicles have some known faults that cause code P0420. Check the operation of the inlet check valves. Make sure the crankcase vent is not clogged, causing the engine to burn oil that clogs the catalytic converter.

Check for exhaust leaks around any bends in the exhaust pipe (common cause). Check for any O2 sensor trouble codes.

If no problems are found, replace the converter. This is a very common problem on both 1.8 T and V6 petrol engines. The 1.8 T catalytic converter can be quite difficult to replace if you are not experienced with it.

The V6 has two catalytic converters, so make sure you troubleshoot and replace the correct side of the catalytic converter.

Error P0011

Malfunction code P0011 actually has no effect on the behavior of the vehicle. P0011 – camshaft position error. But, running the camshaft ahead does not allow the engine to function in optimal conditions. All this leads to such unpleasant consequences as increased fuel consumption and increased emissions of harmful substances into the atmosphere.

To resolve P0011, the following procedure is recommended:

1. Check the phase sensor contacts for oxidation. If damage is detected, it is worth replacing the mechanism or the contacts themselves.
2. Visually assess the condition of the phase sensor. It may have suffered mechanical damage. In this case, only replacing the device will help.
3. Using a multimeter set to “Ohmmeter” operating mode, check the VTT valves of the gas distribution system.
4. Inspect the camshaft teeth, which also tend to wear out.

It is worth noting that error P0011 often occurs due to untimely maintenance, as well as due to the use of low-quality engine oil. Hyundai, Subaru, and Peugeot cars are especially sensitive to such a malfunction.

Conclusion

• In most cases, the catalytic converter is faulty and is indicated by the P0420 code. But there may be other reasons why the catalyst was damaged. Always correct all other trouble codes before troubleshooting P0420.
• You can use special tools or reprogram the control unit to trick it. This will help get rid of the P0420 code.
• Bank 1, Bank 2 indicate which O2 sensor or catalytic converter is faulty.
• The catalytic converter cleans the exhaust gases and its removal is illegal.

Previous post Error P0123 - what it means, symptoms, causes, diagnosis, solution

Next entry Error P0190 - what it means, symptoms, causes, diagnosis, solution

Error P0335

P0335 indicates a problem with the crankshaft sensor circuit. Most often, the problem occurs due to a breakdown of the crankshaft position sensor. An engine with a faulty crankshaft position sensor has difficulty starting when cold. At the same time, power decreases and the vehicle's dynamic performance decreases. To identify and subsequently eliminate the problem, you can conduct an independent diagnosis of DPKV.

The mechanism itself fails in rare cases. A breakdown can be caused by a foreign object or other mechanical impact. If the device visually looks completely intact, it will have to be removed for subsequent inspection. Using a multimeter set to “Ohmmeter” mode, the resistance on the DPKV winding is measured. A normal reading is considered to be a resistance of 550-750 Ohms. In case of any deviations from the norm, it is best to replace the mechanism with a new copy.