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

Solution

1. Preparation

• Gather tools and necessary parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before working on any exhaust components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, socket set, torque wrench
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust pipe.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors.
  4. Install the new sensors and torque them to the manufacturer's specification (typically around 30-40 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, jack and jack stands, exhaust gasket, torque wrench
• Sub-steps:
  1. Lift the vehicle using a jack and secure it with jack stands.
  2. Disconnect the exhaust system from the catalytic converter (unbolt the flange or cut if necessary).
  3. Remove the catalytic converter from its mounts.
  4. Install the new catalytic converter with the new gasket, ensuring proper alignment.
  5. Reattach the exhaust system and torque bolts to the manufacturer's specification.

4. Clear Codes and Test Drive

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