how to fix P0420 code on my Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before working on exhaust components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet and extension, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer's specifications (typically around 30-40 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter or saw, hangers and brackets.
• Sub-steps:
  1. If the catalytic converter is suspected to be faulty, remove it from the exhaust system. Use an exhaust pipe cutter to cut the pipes if necessary.
  2. Install the new catalytic converter, ensuring it is aligned properly with the exhaust system.
  3. Secure it with hangers and brackets, tightening to the manufacturer's specifications.
  4. Reconnect any exhaust components that were removed.

4. Clear the Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the system.
  3. Start the vehicle and let it idle for a few minutes.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.