Honda Pilot P0420 (Meaning, Causes, & Fixing) of 2024

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If you own a Honda Pilot and have encountered the dreaded Honda Pilot P0420 error code, you’re not alone.

Understanding what this code signifies and how to address it is crucial for maintaining the performance and longevity of your vehicle.

Honda Pilot P0420


The Honda Pilot is a popular SUV known for its reliability and versatility, making it a favorite among families and adventurers alike.

However, like any vehicle, the Pilot is not immune to mechanical issues, one of which is the P0420 code.

What is the P0420 Code?

The P0420 code indicates a problem with the catalytic converter in your Honda Pilot. The catalytic converter plays a vital role in reducing harmful emissions by converting toxic gases into less harmful substances.

When the onboard diagnostics system detects that the catalytic converter is not functioning properly, it triggers the P0420 code.

Common Causes of the P0420 Code

Several factors can contribute to the triggering of the P0420 code in a Honda Pilot. These include:

  1. Catalytic Converter Failure: Over time, the catalytic converter may become clogged or damaged, leading to inefficient operation.
  2. Oxygen Sensor Issues: Malfunctioning oxygen sensors can provide inaccurate readings to the vehicle’s computer, triggering the P0420 code.
  3. Exhaust Leaks: Leaks in the exhaust system can allow unburned fuel to enter the catalytic converter, causing it to overheat and fail.

Symptoms of a P0420 Code

Detecting the P0420 code early is essential for preventing further damage to your Honda Pilot. Some common symptoms associated with this code include:

  • Check Engine Light: The most obvious indicator of a P0420 code is the illumination of the check engine light on the dashboard.
  • Decreased Fuel Efficiency: A failing catalytic converter can lead to decreased fuel efficiency as the engine struggles to burn fuel efficiently.
  • Reduced Engine Performance: You may notice a decrease in overall engine performance, including sluggish acceleration and rough idling.

Diagnostic Process for the P0420 Code

Diagnosing the P0420 code typically involves a series of steps to pinpoint the exact cause of the issue. A mechanic may perform the following tests:

  1. OBD-II Scan: Using a diagnostic scanner, the mechanic will retrieve the trouble codes stored in the vehicle’s onboard computer.
  2. Exhaust System Inspection: A visual inspection of the exhaust system can help identify any leaks or damage.
  3. Oxygen Sensor Testing: Testing the oxygen sensors can determine if they are providing accurate readings to the vehicle’s computer.
  4. Catalytic Converter Efficiency Test: Specialized diagnostic tools can assess the efficiency of the catalytic converter in converting harmful gases.

Common Fixes for the Honda Pilot P0420 Code

Once the underlying cause of the P0420 code is identified, several repair options are available:

  1. Catalytic Converter Replacement: If the catalytic converter is deemed faulty, replacement may be necessary to resolve the issue.
  2. Oxygen Sensor Replacement: Malfunctioning oxygen sensors can often be replaced to restore proper engine performance.
  3. Exhaust System Repair: Repairing any leaks or damage in the exhaust system can prevent further issues with the catalytic converter.

Preventive Measures to Avoid Recurrence

To prevent the P0420 code from reoccurring in the future, consider the following preventive measures:

  • Regular Maintenance: Adhering to the manufacturer’s recommended maintenance schedule can help keep your Honda Pilot running smoothly.
  • Quality Fuel: Using high-quality fuel can reduce the buildup of carbon deposits in the engine and exhaust system.
  • Avoiding Rough Driving: Avoid aggressive driving habits that can put unnecessary stress on the catalytic converter and other engine components.

Cost Considerations for P0420 Code Repairs

The cost of repairing a P0420 code in a Honda Pilot can vary depending on several factors, including the extent of the damage and the chosen repair option.

Generally, expect to pay anywhere from $200 to $1500 for repairs, with catalytic converter replacement being the most expensive option.

Seeking Professional Help

While some DIY enthusiasts may attempt to diagnose and repair the P0420 code themselves, it’s often best to seek professional help.

A qualified mechanic can accurately diagnose the issue and recommend the most cost-effective solution.

DIY vs. Professional Repair

While DIY repairs may seem like a cost-effective option, they can often lead to further complications if not performed correctly.

For complex issues like the P0420 code, it’s advisable to leave repairs to the professionals who have the necessary tools and expertise.

Warranty and Extended Coverage

If your Honda Pilot is still under warranty, repairs for the P0420 code may be covered, saving you money on out-of-pocket expenses.

Additionally, consider investing in an extended warranty plan for added peace of mind against future mechanical issues.

Driving with a P0420 Code

While it may be tempting to ignore the P0420 code and continue driving your Honda Pilot, doing so can lead to further damage and potential safety hazards.

It’s essential to address the issue promptly to avoid costly repairs down the road.

Environmental Impact of Catalytic Converter Issues

Catalytic converter problems not only affect the performance of your vehicle but also have significant environmental implications.

A malfunctioning catalytic converter can increase harmful emissions, contributing to air pollution and environmental degradation.

Community Insights and Experiences

Many Honda Pilot owners have shared their experiences dealing with the P0420 code online.

Some have found success with simple fixes like replacing oxygen sensors, while others have had to resort to costly catalytic converter replacements.

Joining online forums and communities can provide valuable insights and support for addressing this issue.

Future Trends in Catalytic Converter Technology

As automotive technology continues to evolve, so too does catalytic converter technology.

Manufacturers are constantly innovating to develop more efficient and environmentally friendly catalytic converters that meet stringent emissions standards.

Keep an eye on future advancements that may offer solutions to common catalytic converter issues.

People also ask

How do I fix my Honda P0420 code?

To fix a Honda P0420 code, you may need to:

Check Oxygen Sensors: Inspect and potentially replace oxygen sensors if they are faulty.
Examine Catalytic Converter: Evaluate the catalytic converter for damage or inefficiency and replace if necessary.
Address Exhaust Leaks: Repair any leaks in the exhaust system that could affect catalytic converter performance.
Reset Error Codes: After repairs, reset the error codes using a diagnostic tool or by disconnecting the car battery for a few minutes.

What is the code P0420 on a pilot?

The P0420 code on a Honda Pilot typically indicates a problem with the catalytic converter efficiency.

This means that the catalytic converter is not performing as efficiently as it should in reducing harmful emissions.

Common causes for this code include a faulty catalytic converter, oxygen sensor issues, exhaust leaks, or engine misfires.

It’s recommended to diagnose and address the underlying issue promptly to prevent further damage to the vehicle and ensure compliance with emissions regulations.

Is it bad to drive with a P0420 code?

Driving with a P0420 code is generally not recommended for an extended period as it indicates a problem with the catalytic converter’s efficiency.

Continuing to drive with this code may lead to further damage to the catalytic converter or other components of the vehicle’s emission control system.

It’s best to have the issue diagnosed and repaired by a qualified mechanic as soon as possible to ensure the vehicle’s proper operation and compliance with emissions regulations.

Which O2 sensor throws a P0420 code?

Typically, the downstream or rear oxygen sensor (O2 sensor) is responsible for triggering a P0420 code.

This sensor measures the oxygen levels after the catalytic converter and helps determine its efficiency.

If the downstream O2 sensor detects that the catalytic converter is not effectively reducing emissions, it will trigger the P0420 code.

However, it’s essential to diagnose the issue properly, as other factors like the upstream O2 sensor, exhaust leaks, or engine misfires could also contribute to the code.


Dealing with the P0420 code in your Honda Pilot can be frustrating, but understanding the underlying causes and repair options can help alleviate some of the stress.

Whether you choose to tackle the issue yourself or seek professional help, addressing the P0420 code promptly is essential for maintaining the performance and longevity of your vehicle.

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