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P0420 Nissan Error Code: Symptoms, Causes, & Fixes

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P0420 Nissan Error Code: Symptoms, Causes, & Fixes

The P0420 Nissan error code is a signal from your car’s engine control unit (ECU) that there’s a problem with the efficiency of the catalytic converter.

More details:

  • What is the P0420 code? This code is often titled “Catalyst System Efficiency Below Threshold.” It signifies that the catalytic converter, an essential part of your vehicle’s exhaust system, is not functioning at optimal efficiency.
  • How is it detected? The P0420 code is determined by the readings from the downstream oxygen sensor. This sensor monitors the exhaust gases after they pass through the catalytic converter.
  • What triggers it? If the downstream oxygen sensor detects an abnormal amount of pollutants in the exhaust gases, it signals the ECU, and the P0420 code is triggered.
  • What else to consider? While this code is commonly linked to a problematic catalytic converter, other issues could cause this error as well. Faulty oxygen sensors, exhaust leaks, or issues with the fuel mixture could also trigger the P0420 code. A comprehensive diagnosis is always recommended to identify the actual problem.
Possible Causes of Nissan P0420Potential FixesEstimated Cost to Fix
Faulty Catalytic ConverterReplace the Catalytic Converter$945 – $2475
Oxygen (O2) sensor not working correctlyReplace the O2 sensor$200 – $300
Leak in the exhaust systemRepair the exhaust system$100 – $200 (can vary widely)
Damaged or failing spark plugs or wiresReplace spark plugs and wires$150 – $400
Bad fuel injectorReplace or repair fuel injector$800 – $1450

Nissan cars in America have surged in popularity recently, with the company selling over a million vehicles per year. However, like all cars, Nissans are not immune to issues. One common issue that owners may face is the P0420 error code.

If you’re driving a Nissan car, there’s a good chance you’ve seen the P0420 error code. This code signifies that the catalytic converter is not functioning efficiently and can cause various problems with your car.

If you see the P0420 error code on your Nissan car, there are a few things you can do to fix it. One option is to take your vehicle to a mechanic and have them replace the catalytic converter. Another option is to buy a replacement catalytic converter and install it yourself. This article will discuss the causes of this error and how to fix it.

P0420 Nissan Error Code – Symptoms

nissan error code p0420
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While the P0420 error code is most commonly associated with the catalytic converter, this can cause a few issues with the running of your car.

Decreased Fuel Efficiency

The most common symptom of the P0420 error code is a decrease in fuel efficiency. This is because the catalytic converter is not converting the exhaust gases into less harmful substances as efficiently as it should.

As a result, your car will have to work harder to produce the same amount of power, which uses more fuel.

Engine Running Louder

You may also notice that your car’s engine is running louder than usual. A louder engine is because the exhaust gases are not converted correctly, and they exit the vehicle through the exhaust system.

Reduced Engine Power

Another symptom of the P0420 error code is reduced engine power. When the catalytic converter is not functioning correctly, the engine does not run as efficiently. A less efficient engine can lead to a loss of power and reduced performance.

Engine Misfire

Another symptom of the P0420 error code is engine misfires. The catalytic converter is responsible for converting exhaust gases into less harmful substances. If it’s not working properly, the engine may misfire.

P0420 Nissan Error Code – Causes

catalytic converter
Photo by: Wikimedia Commons

Now that we’ve gone over the symptoms of the P0420 error code let’s look at the causes.

Clogged Catalytic Converter

A clogged catalytic converter is one of the most common causes of the Nissan P0420 error code. The catalytic converter contains a honeycomb-shaped structure that is coated with a catalyst. Over time, this structure can become clogged with soot and other materials.

When this happens, the catalytic converter cannot convert the exhaust gases properly, and it will trigger the P0420 error code.

Failed Oxygen Sensor

Another common cause of the Nissan P0420 error code is a failed oxygen sensor. The oxygen sensor measures the amount of oxygen in the exhaust gases. If it’s not working properly, it can cause the P0420 error code to be triggered.

Exhaust System Leak

Another potential cause of the P0420 error code is an exhaust system leak. If there’s a hole in the exhaust pipe or the exhaust manifold, it can allow oxygen to enter the system. This can cause the P0420 error code to be triggered.

Understanding Oxygen Sensor Readings and the Catalytic Converter

When a vehicle’s powertrain control module (PCM) identifies that the catalytic converter is not operating optimally, it’s often a result of discrepancies between its two oxygen sensors. Positioned both upstream and downstream of the converter, these sensors are pivotal in measuring exhaust gas oxygen levels.

Ideally, the upstream oxygen sensor’s readings should vary when the vehicle reaches its operational temperature and operates in a closed loop. Conversely, a properly functioning downstream sensor, coupled with an efficient catalytic converter, should produce stable readings. However, if both sensors mirror each other in terms of readings, it signifies converter inefficiency.

Notably, if the downstream sensor’s voltage starts to fluctuate similarly to the upstream one, it indicates heightened oxygen levels. In such situations, the PCM logs the P0420 error code and activates the check engine light.

P0420 Nissan Error Code – Fixes

fixing car tools
Photo by: Pixabay

Now that we’ve gone over the symptoms and causes of the P0420 error code let’s look at the fixes.

Use A Catalytic Converter Cleaner

One of the easiest ways to fix the P0420 error code is to use a catalytic converter cleaner. These cleaners are designed to clean the honeycomb structure of the catalytic converter and remove any build-up that may be causing problems.

You can find these cleaners at most auto parts stores. Add it to your gas tank, drive for 150 miles, and the cleaner will work its way into the system.

Replace The Oxygen Sensor

Another potential fix for the P0420 error code is to replace the oxygen sensor. If the oxygen sensor is faulty, it can cause the P0420 error code to be triggered.

You can find oxygen sensors at most auto parts stores. Remove the old oxygen sensor and install the new one in its place.

Repair The Exhaust System

If the exhaust pipe is leaking, it can cause the P0420 error code to be triggered. The best way to fix this problem is to take your car to a mechanic and have them repair the leak. Most of the technicians will use an OBD-II scanner to retrieve the particular code before repairing.

They will be able to identify the leak and make the necessary repairs.

Replace the Catalytic Converter

One option for fixing the P0420 error code is to replace the catalytic converter. This is a relatively straightforward process; it can be done by taking your car to a mechanic.

If you’re mechanically inclined, you may also be able to replace the catalytic converter yourself. However, it’s important to note that this is an advanced process, and it’s important to follow the instructions carefully.

If you want to change the catalytic converter on your Nissan vehicle, numerous guides are available to help you.

PS: If you have another error called p1701 then visit this page instead : https://yourmotorguide.com/p1701-nissan-code/


What Is The Function Of The Catalytic Converter?

The catalytic converter is a vital part of a car’s exhaust system. It is typically located between the car’s engine and the muffler. The converter’s job is to convert harmful pollutants in the exhaust into less harmful emissions before they are released into the atmosphere.

This conversion is accomplished by using a catalyst typically made of platinum or palladium. The catalytic converter is an essential component of a car’s emission control system and helps keep the air clean.

Why Am I Still Getting A P0420 Code After Replacing My Catalytic Converter?

There are a few potential reasons you might still be getting a P0420 code after replacing your catalytic converter. One possibility is that there is a leak in your exhaust system. Another option is that the converter is not installed correctly. If you’re still getting the P0420 code after replacing the catalytic converter, it’s best to take your car to a mechanic and have them diagnose the problem.

How Much Does P0420 Repair Cost?

The cost of repairing the P0420 error code can vary depending on the cause. If you need to replace the catalytic converter, the cost can range from $500 to $2000. If you need to replace the oxygen sensor, the cost can range from $100 to $200.

The cost of repairing a leak in the exhaust system will vary according to the amount of damage. A minor repair might cost $100, while a more extensive repair might cost $1000 or more. Ultimately, the cost of repairing the P0420 error code will depend on the cause of the problem.

Which o2 sensor causes P0420?

The P0420 code is typically triggered by the downstream oxygen sensor, also known as the post-catalytic sensor. This sensor is located after the catalytic converter in the exhaust system.

More information: The downstream oxygen sensor monitors the level of oxygen in the exhaust gases after they’ve been processed by the catalytic converter. Its main function is to provide feedback to the car’s engine control unit about the efficiency of the converter.

If the converter isn’t functioning properly, it can lead to abnormal readings by the downstream O2 sensor, triggering a P0420 code. However, remember that the P0420 code doesn’t necessarily mean the sensor itself is faulty – it could be indicating another issue, like a malfunctioning catalytic converter, an exhaust leak, or a poor fuel mixture.

Can spark plugs cause P0420?

Yes, damaged or failing spark plugs can indeed cause the P0420 code. If spark plugs aren’t working properly, they can lead to unburned fuel entering the catalytic converter, which can damage it and trigger the P0420 code.

If you suspect your spark plugs might be the issue, consider having them inspected or replaced.

What is P0420 starting problems?

The P0420 code itself doesn’t directly cause starting problems in a vehicle. However, it indicates that the catalytic converter isn’t working as efficiently as it should. If the converter is severely damaged, it could potentially lead to issues like engine misfires or reduced performance, which may affect starting the vehicle.

Always consult with a professional if you’re experiencing starting problems along with a P0420 code.

Can fuel injectors cause P0420?

Absolutely, bad fuel injectors can cause the P0420 code. If a fuel injector is leaking or not delivering the correct amount of fuel, it can lead to a rich or lean condition.

This may cause the catalytic converter to work harder than it’s designed to, eventually leading to its failure and triggering the P0420 code. If you’re experiencing this issue, a fuel injector repair or replacement might be needed.

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