how to fix P0420 code on Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Use an O2 sensor socket to remove the sensors.
  • Inspect the wiring and connectors for damage.
  • Install new oxygen sensors, tightening them to the manufacturer's specifications (typically around 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  • If the oxygen sensors are functioning correctly, proceed to inspect the catalytic converter.
  • Remove any heat shields and exhaust components as necessary.
  • Unbolt the catalytic converter from the exhaust system using a socket set.
  • Install the new catalytic converter, ensuring all gaskets and seals are replaced to prevent exhaust leaks.
  • Torque bolts to the specified values (check the service manual for exact specifications).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.

5. Test Drive the Vehicle

• Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor for any symptoms.