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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors. The upstream sensor is before the catalytic converter, and the downstream sensor is after it.
  2. Disconnect the electrical connectors for both sensors.
  3. Remove the sensors using an oxygen sensor socket or wrench.
  4. Install the new sensors, ensuring they are tightened to manufacturer specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Remove any heat shields or brackets securing the catalytic converter.
  2. Disconnect the exhaust pipes from both sides of the catalytic converter using a socket set.
  3. Remove the catalytic converter from its mounting points.
  4. Install the new catalytic converter, ensuring proper alignment and fitment.
  5. Reconnect the exhaust pipes and secure them using new gaskets if necessary.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery.
  2. Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.