FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
how to fix P0420 code on Honda Accord 9th Generation (2013-2017) - Honda Accord
Home/Cars/Honda/Accord/9th Generation (2013-2017)/how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

Honda Accord 9th Generation (2013-2017)

Error Codes
2-4 hours
Time
medium
Difficulty
high
Severity
Error Code: P0420
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
3 min read
526 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0420 exhaust system issue in Honda Accord 9th Generation (2013-2017). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0420
Affected Component
Exhaust System
Estimated Time
2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

  • •Disconnect the battery before working on electrical systems.
  • •Allow the engine to cool before inspecting or working on the exhaust system.

Symptoms

  • •Check engine light illuminated
  • •Decreased fuel efficiency
  • •Rough idle or stalling
  • •Increased exhaust emissions
  • •Unusual engine noises (e.g., rattling from the catalytic converter)

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

  • ✓Test the affected component to ensure it functions correctly
  • ✓Check for any error codes or warning lights
  • ✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • •OBD-II scanner
  • •Oxygen sensor socket
  • •Socket set
  • •Torque wrench
  • •Multimeter

Parts Required

  • •Upstream oxygen sensor
  • •Downstream oxygen sensor
  • •Catalytic converter (if necessary)
  • •Exhaust gaskets

Additional Information

Error Code
P0420
Affected Component
Exhaust System
Estimated Time
2-4 hours
Difficulty
medium
Severity
high
Tools Required
5 items
Parts Required
4 items

Related Faults

Loading...

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation
Solution
1. Preparation
  • Gather tools and parts.
  • Ensure the vehicle is parked on a level surface and the engine is cool.
  • Disconnect the negative battery terminal to prevent electrical shock.
2. Inspect and Replace Oxygen Sensors

  1. Locate the Oxygen Sensors

    • Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.

  2. Remove the Oxygen Sensors

    • Use an oxygen sensor socket to carefully unscrew and remove the sensors.
    • Note the orientation for reinstallation.

  3. Install New Oxygen Sensors

    • Apply anti-seize compound to the threads of the new sensors.
    • Install the new sensors and torque them to manufacturer specifications (typically around 30 ft-lbs).
3. Inspect and Replace Catalytic Converter (if necessary)

  1. Inspect Catalytic Converter

    • Check for physical damage, rattling sounds, or excessive heat.
    • If damaged, proceed with replacement.

  2. Remove the Old Catalytic Converter

    • Use a socket set to unbolt the catalytic converter from the exhaust system.
    • Carefully remove any heat shields and gaskets.

  3. Install New Catalytic Converter

    • Position the new catalytic converter in place.
    • Use new gaskets and bolts, tightening to the manufacturer’s torque specifications (typically around 30-35 ft-lbs).
4. Reset the Check Engine Light
  • Reconnect the negative battery terminal.
  • Use the OBD-II scanner to clear the P0420 code.
5. Test the System
  • Start the engine and allow it to reach operating temperature.
  • Perform a test drive to ensure the check engine light remains off.