Automakers kept adding features to newer cars, and this also changed the environmental impact of cars. Older cars created emissions every time you drove them as harmful gases exited the exhaust tailpipe.
Automakers saw this as a significant issue and implemented the catalytic converter to remediate the issues. The catalytic converter is primarily designed to change harmful gases from the combustion chamber to less toxic gases before they exit into the environment.
The work of the catalytic convert is so important to the operation of the car that if it fails to do its job, the vehicle will emit harmful gases into the atmosphere and will fail an emissions test. Band each engine has two O2 sensors on the exhaust pipes.
The O2 sensors monitor and measure the level of pollution entering the environment and then signal the powertrain control module.
For example, if the O2 sensors in bank 1 note that the cat system efficiency in bank 1 is below a threshold they will signal the ECM, which will log a P0420 code in its memory.
What does error code P0420 mean?
A P0420 indicates that the PCM has found a problem with the catalytic converters. As said above, the catalytic converter converts toxic gas from the combustion chamber into less harmful gas before expelling it into the atmosphere.
The converter does this through the use of rhodium, gold, platinum, and palladium mesh filters. If the Upper O2 sensor is working correctly, it will produce a fluctuating signal, as the vehicle is operating properly, and is in a closed loop with a proper temperature.
The lower oxygen sensor will show a steady reading when it’s working properly, and the catalyst converter is fine.
If both the upstream and downstream have the same or similar readings, it would mean that the catalytic converter is bad. If the downstream O2 sensor starts fluctuating just like the upstream, it indicates too much oxygen is present in the engine.
The engine control unit (ECU) will register a P0420, and the check engine light would shine on the dashboard to alert the driver of an impending checkup regarding the engine.
What is the symptom of error code P0420?
A P0420 code on a Ford or any vehicle does not display any obvious signs of a faulty catalytic converter or any drivability symptoms. However, here are a few possible symptoms that can indicate the PCM has set a P0420 code.
#1. Check engine light.
There are several things that can factor into the vehicle computer displaying a check engine light on the dashboard, including a P0420 code bank 1. When the ECM determines that the catalytic converters system is below the threshold bank 1, it will trigger the check engine light to indicate potential issues in the system.
Although, when the check engine light illuminates on the dashboard, you will have to diagnose your vehicle as you can’t just visually see what the problem is just by looking at the warning light.
#2. The vehicle may not exceed a certain speed level.
Depending on the seriousness of the P0420 on a Daihatsu or your respective vehicle, the vehicle could display up to a maximum of 30-40 mph; unless of course you’re on the freeway/hwy and surpass this speed, you may not notice it.
#3. Power loss.
When the powertrain control module has found an issue in bank 1 catalytic converter, the engine may not function efficiently based on engine temperature. As an example, you may notice a loss in engine power when you are driving.
#4. Rotten egg smell.
Sulfur or rotten egg smell is a common symptom related to a bad catalyst converter; this horrible smell results from overabundance of sulfur created by the high level of dissimilar amounts of oxygen in the exhaust system causing a high level of sulfur to be in the gas tank. Which brings created that awful odor of a rotten egg smell.
And some other symptoms you may see include:
- Poor Fuel Economy
- Engine Burning Oil
- Smoke From The Tailpipe
- Hard Shifting, Rough Idles, And Engine Misfire
- Air-Fuel Imbalance
What Causes error code P0420?
Several factors can cause a car to trigger diagnostic trouble code P0420 in either Toyota or any car model. This can make the error a challenge to diagnosis and repair.
- Engine running rich or lean
- Malfunctioning O2 sensor upstream or downstream
- Leaking fuel injectors
- Bad catalytic converter
- Bad engine coolant temp sensor
- Increased fuel pressure
- Wiring issues O2 sensor
- Front or rear O2 sensor malfunction
- Use wrong fuel
- Bad exhaust tail pipe
- Damaged muffler
- Defective exhaust manifold
- Dirty oil in catalytic converter
How serious is problem error code P0420?
P0420 error code is a moderate case. It may not be a serious case, but it can create some highway issues, specifically when attempting to overtake another vehicle. Unfortunately, the sad story is, the fact that if you travel these roads continuously, you will not know you are experiencing P0420 problems until you want to overtake a car traveling highway speeds.
If the catalytic converter problems develop, these problems may seem arbitrary, but if you do not drive over 65 mph, you may see no problems occurring. However, if you do city driving, you may never perceive that the vehicle has some acceleration issues.
The sad story is, all converters are expensive, and if this error is not repaired properly, the failure will cause damage to components.
How do you fix P0420?
There are many causes involved with P0420 error code, so the first action to help fix is to properly diagnosis the root cause of the issue. Here are some items for you to do to repair the issues.
- Replace catalytic converter (generally the cause)
- Diagnose and repair any engine misfire issues
- Repair leaking muffler, or replace muffler
- Repair leaking exhaust pipes, or replace exhaust pipes
- Repair leaking exhaust manifolds, or replace exhaust manifolds
- Replace bad oxygen sensors
- Replace bad engine coolant temp sensor
- Repair or replace bad/injectors
- Repair oxygen sensor connector, or replace
- Repair O2 sensor wiring.
Common P0420 Diagnosis Mistakes
The most common mistakes mechanics make when repairing P0420 is they suspect they need to replace parts without a proper diagnosis.
If the powertrain control module (PCM) shows other codes like P0300, P0171, or P0174, you have to repair these codes in addition of the P0420 diagnostic and repair procedures. If these issues are not repaired, you can damage the catalytic converter oxygen sensors and return to a P0420 issue again.
How to Diagnose
If you want to solve P0420 catalyst system efficiency below threshold bank 1 at home and avoid paying service charges, this is a good guide for a simpler diagnosing method.
This is not an intermediate or beginner guide, as this is a labor-intensive task that takes a lot of time.
- Parts and Items Needed
- Scan tool
- Digital multimeter
Step 1: Diagnose the vehicle
Find the OBD port on your vehicle and plug the scan tool in. Then proceed to diagnose the vehicle, and check to see if there are any problems. If any code comes up aside from P0420, trace the root cause and fix it before moving on to the next diagnostic step.
Step 2: Inspect the exhaust system
Inspect exhaust system components, look for leaks or damages, such as checking the manifold gasket, O2 sensors, and exhaust pipes. If you notice any leaks or damaged components, repair or replace the exhaust part and locate the fault code again and erase it.
Now, do an actual test, and run the vehicle for about 20 to 30 minutes. After that, scan your vehicle again to see if the codes are still present. After that, proceed to the next step.
Step 3: Test the downstream oxygen sensor
Start the engine and let it idle until the engine reaches average operating temperature. Under idling conditions, using the multimeter, test the downstream O2 sensor and record the voltage reading.
A good downstream O2 sensor will be around 0.45v and will be a signal showing the catalytic converter is working; however, voltage that oscillates or varies between 0.1v to 0.9v indicates a bad catalyst converter that either needs to be cleaned or potentially replaced.
What is the cost of fixing a P0420?
The P0420 error codes can be caused by various factors, and it is impossible to estimate the cost of repairs without a proper diagnosis.
You can visit an auto repair shop have a technician diagnose the cause of the problem. Most service technicians will charge you for 1 hour of diagnostic time.
The average hourly auto repair rate is between $75 to $150. After the diagnosis, the service technician can give you an estimate for the repair cost and fix the P0420 error codes.
Your diagnosis will likely lead to one or more of the parts resulting in the problem. The prices quoted are average estimations, meaning they can be higher or lower than the prices mentioned.
- Air fuel sensor: $150 – $200
- Catalytic converter: $500 – $1000
- Replace oxygen sensor: $200 – $300
- Exhaust leak: $150 – $250
FAQs.
Q: What can cause P0420?
The ECM can request a P0420 error code for a number of reasons. Here’s the most common related to the vehicle.
- Engine misfire
- Engine is lean or rich
- Contaminated oil in the catalytic converter
- Malfunctioning engine coolant temp sensor
- Wrong or loose O2 sensor wiring connection
- Exhaust malfunction
- O2 sensor
- Bad exhaust manifold
- Bad exhaust muffler
- Bad exhaust pipe
- Leaking fuel injector
- More than normal fuel pressure
Q: Is it okay to drive with P0420?
You can drive with a P0420 until you reach your destination or mechanic shop. In certain areas, you may drive with it for a few weeks until you get the money to address the issue.
However, if you ignore the P0420 error code and drive the vehicle beyond a couple of days, you will expose the catalytic converter to a cat failure and potentially other connected parts.
Q: Will a catalytic converter cleaner fix P0420?
Yes. To fix the OBD P0420 code, you can use a catalytic converter cleaner. Simply obtain a catalyst converter cleaner, and pour the entire can in the gas. Clear the P0420 code bank 1.
Next, drive the vehicle for 30 minutes at 45 mph or higher. This will fix the P0420 if a bad catalyst converter was a part of the problem.
Q: Will P0420 clear itself?
The error code of P0420 on a Nissan model or any car model, won’t clear itself. You will either track the cause of the problem and fix it, or you’ll have to use the scanner to clear error code, or codes, for it to disappear.
Keep in mind, you may choose to erase codes with scan tool without addressing the problem; however, this does not solve problem. It will remove the code from the Vehicle’s memory for that time period. Before long, the code will reappear.
Q: Can an O2 sensor cause a P0420 code?
Yes. The O2 sensors monitor and regulates the amount of oxygen in the exhaust gases and transmittle this information to the vehicle computer. The downstream O2 sensor monitors the efficiency of the catalyst converter, and the upstream O2 sensor sends a reference point of efficient ratio.
So if either of these sensors failed, they can present false readings to the ECU and the vehicle throws the P0420 error code on you for SUZUKI or your respective car model.
Final Words
A catalyst converter is an important part of the powertrain that changes dangerous gases from the combustion chamber into less toxic gases before releasing them into the atmosphere. This is why we should make sure they are functional all the time.
Eventually, nothing lasts forever, and they can break down and need replacing or repairs. Several reasons other than the catalyst converter can cause the powertrain control module to throw a DTC P0420 on Honda or any car model.
Whatever is causing the P0420, regardless of the consequence, find out what it is, and make the repairs before the issue leads down the path of system failures.