how to fix code P0420 on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery negative terminal to ensure safety.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an oxygen sensor socket to remove the sensors from the exhaust pipe.
  4. Install the new oxygen sensors in reverse order, ensuring they are securely tightened (typically 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove any heat shields or brackets securing the catalytic converter using a socket set.
  2. Unbolt the catalytic converter from the exhaust system using a wrench.
  3. Inspect the old catalytic converter for signs of damage or clogging.
  4. Install the new catalytic converter, ensuring proper alignment and torque (typically 25-30 ft-lbs).
  5. Reinstall any heat shields or brackets.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code from the ECM.
  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 return.