Nissan Error Code P0420 ~ Symptoms and How to Fix

If you own a Nissan vehicle and have come across the Nissan error code P0420, it’s essential to understand its significance and how to address it.

This article will guide you through the various aspects of Nissan error code P0420, including its causes, symptoms, diagnostic process, potential fixes, preventive measures, and more.

By the end, you’ll have a comprehensive understanding of this error code and be equipped to handle it effectively.

When the onboard diagnostic system of your Nissan detects an issue with the efficiency of the catalytic converter, it triggers error code P0420.

The catalytic converter is responsible for reducing harmful emissions from the vehicle’s exhaust. A malfunctioning converter can lead to increased pollution and decreased engine performance.

Understanding Error Code P0420

Error code P0420 specifically indicates that the catalytic converter’s efficiency is below the expected threshold.

The onboard diagnostic system monitors the levels of oxygen before and after the converter. If the reduction in emissions is not significant enough, it signifies a problem with the converter’s performance.

Causes of Nissan Error Code P0420

Nissan Error code P0240

Catalytic Converter Efficiency

The primary cause of error code P0420 is a drop in the efficiency of the catalytic converter. Over time, the converter may become clogged or damaged, leading to reduced effectiveness in reducing emissions.

Oxygen Sensor Functionality

Faulty oxygen sensors can also trigger error code P0420. These sensors measure the oxygen levels in the exhaust gases and provide feedback to the engine control unit.

If the oxygen sensors are not functioning correctly, it can result in an inaccurate reading of the converter’s efficiency.

Exhaust System Leaks

Leaks in the exhaust system, such as cracks or damaged gaskets, can cause error code P0420.

These leaks allow unmeasured air to enter the exhaust stream, disrupting the converter’s performance and triggering the error code.

Also Read: Can Low Oil Cause the EPC Light to Turn On in Your Car ?

Symptoms of Nissan Error Code P0420

Check Engine Light

Nissan Error Code P0420

The most common symptom of error code P0420 is the illumination of the check engine light on the vehicle’s dashboard.

It serves as a warning that a potential issue with the catalytic converter or oxygen sensors has been detected.

Reduced Engine Performance

Nissan Error code P0240

A drop in engine performance can occur due to error code P0420. You may experience a decrease in acceleration, power, and overall responsiveness of your Nissan vehicle.

Increased Fuel Consumption

Nissan Error code P0240

If the catalytic converter is not functioning optimally, it can lead to increased fuel consumption. Your vehicle may require more fuel to compensate for the reduced efficiency of the converter.

Diagnostic Process for Nissan Error Code P0420

To identify the cause of error code P0420, a diagnostic process is necessary. Here are the steps involved:

OBD-II Scanner

Using an OBD-II scanner, you can retrieve the specific error code from your Nissan’s onboard diagnostic system.

This code helps pinpoint the issue and provides a starting point for further investigation.

Visual Inspection

A visual inspection of the exhaust system can reveal any visible leaks, damage, or corrosion. Look for cracks, holes, or loose connections in the exhaust pipes and manifold.

Testing Oxygen Sensors

Testing the oxygen sensors will help determine if they are functioning correctly. This can be done using a multimeter or a specialized sensor testing tool. Replace any faulty sensors as necessary.

Checking the Catalytic Converter

The catalytic converter can be tested using an exhaust gas analyzer. This test measures the emissions before and after the converter, determining its efficiency.

If the results fall below the required threshold, the converter may need repair or replacement.

Fixing Nissan Error Code P0420

Nissan Error code P0240

Once the cause of error code P0420 has been identified, appropriate steps can be taken to fix it. Here are the potential solutions:

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Repairing or Replacing Oxygen Sensors

If the oxygen sensors are faulty, they should be repaired or replaced. Properly functioning sensors ensure accurate readings and help maintain the catalytic converter’s efficiency.

Repairing Exhaust System Leaks

Any leaks in the exhaust system should be repaired promptly. This may involve replacing damaged components, such as gaskets or sections of the exhaust pipes, to ensure a tight seal.

Replacing the Catalytic Converter

In cases where the catalytic converter is beyond repair, replacement becomes necessary. A new converter will restore the emissions-reducing capabilities of your Nissan’s exhaust system.

Preventive Measures to Avoid Error Code P0420 in Nissan

To minimize the likelihood of encountering error code P0420 in the future, consider the following preventive measures:

Regular Maintenance

Adhering to your Nissan’s recommended maintenance schedule is crucial. Regular servicing helps identify potential issues early on and allows for timely repairs or replacements.

Using High-Quality Fuel

Using high-quality fuel can help maintain the efficiency of the catalytic converter. It reduces the risk of contaminants and deposits that may impair its performance.

Avoiding Engine Misfires

Engine misfires can damage the catalytic converter over time. Address any misfires promptly, as they can contribute to the onset of error code P0420.


Error code P0420 in Nissan vehicles signifies a drop in the efficiency of the catalytic converter. By understanding its causes, symptoms, diagnostic process, and potential fixes, you can effectively address this issue.

Regular maintenance, using high-quality fuel, and avoiding engine misfires are preventive measures that can help you avoid encountering error code P0420.

If you experience this error code, it’s recommended to consult a professional mechanic for an accurate diagnosis and appropriate repairs.


What does Nissan error code P0420 mean?

Error code P0420 in Nissan vehicles indicates a decrease in the efficiency of the catalytic converter. It means that the converter is not effectively reducing harmful emissions to the expected threshold.

Can I drive with the P0420 error code?

While it may be possible to drive with error code P0420, it is not recommended. A malfunctioning catalytic converter can result in reduced engine performance, increased fuel consumption, and potentially lead to further damage if left unaddressed.

How much does it cost to fix error code P0420?

The cost of fixing error code P0420 can vary depending on the underlying cause and the specific repairs required. It can range from replacing oxygen sensors or repairing exhaust system leaks to replacing the catalytic converter. It’s advisable to consult a professional mechanic to get an accurate estimate.

How long does it take to fix P0420?

The time required to fix error code P0420 depends on the cause and the complexity of the repairs. Simple repairs like replacing oxygen sensors or fixing minor exhaust leaks can be completed in a few hours. However, if the catalytic converter needs replacement, it may take longer.

Can I reset the error code P0420 myself?

While it’s possible to reset the error code using an OBD-II scanner or by disconnecting the battery, it will not fix the underlying issue causing error code P0420. It’s crucial to diagnose and address the problem to ensure proper functionality of the catalytic converter.

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