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

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Disconnect the negative battery terminal to prevent electrical issues.

2. Replace Oxygen Sensors (if faulty)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Steps:
  1. Locate the upstream and downstream oxygen sensors near the catalytic converter.
  2. Use the O2 sensor socket to carefully unscrew the faulty sensors.
  3. Apply anti-seize compound to the threads of the new sensors to prevent future seizing.
  4. Install the new sensors and torque to manufacturer specifications (typically around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust sealant, torque wrench
• Steps:
  1. Raise the vehicle securely using jack stands.
  2. Remove any heat shields or components obstructing access to the catalytic converter.
  3. Disconnect the exhaust pipes from the catalytic converter by removing the bolts.
  4. Inspect the catalytic converter for damage; if needed, unbolt and replace it with a new unit.
  5. Reconnect the exhaust pipes and torque bolts to manufacturer specifications.
  6. Reinstall any heat shields and components removed earlier.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• Steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and take the vehicle for a test drive to ensure the code does not return.