how to fix P0420 error on Honda Accord 10th Generation (2018-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and disconnect the electrical connector.
  2. Use the O2 sensor socket to remove the upstream oxygen sensor.
  3. Install the new oxygen sensor, tightening it to the manufacturer's specified torque (usually around 30 lb-ft).
  4. Reconnect the electrical connector securely.

3. Evaluate and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust gasket.
• Sub-steps:
  1. Raise the vehicle and secure it with jack stands.
  2. Disconnect the exhaust pipe from the catalytic converter by removing the bolts.
  3. Remove any additional mounting hardware holding the catalytic converter in place.
  4. Inspect the old catalytic converter for damage; replace it with a new one if necessary.
  5. Reinstall the catalytic converter, ensuring all bolts are tightened to the specified torque.

4. Clear Error Codes

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 error code.

5. Test the System

• Sub-steps:
  1. Start the engine and let it warm up.
  2. Conduct a test drive to ensure the check engine light does not reappear.