how to fix P0420 code on Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Apply penetrating oil to the sensor threads to ease removal.
  3. Disconnect the electrical connectors from both sensors.
  4. Use the O2 sensor socket to remove the sensors.
  5. Install new oxygen sensors and tighten to the manufacturer's specified torque (typically 30-40 lb-ft).
  6. Reconnect the electrical connectors.

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

• Tools Required: Socket set, torque wrench, exhaust pipe cutter, gasket scraper, new exhaust gaskets.
• Sub-steps:
  1. Raise the vehicle securely using jack stands.
  2. Remove the heat shield if applicable.
  3. Disconnect the exhaust pipes from the catalytic converter using a socket set.
  4. Cut any necessary exhaust brackets or supports to free the catalytic converter.
  5. Remove the old catalytic converter and clean the mating surfaces of the exhaust pipes.
  6. Install the new catalytic converter using new gaskets and tighten bolts to the specified torque (typically 30-40 lb-ft).
  7. Reinstall any removed heat shields and components.

4. Clear Codes and Test

• 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 allow it to reach operating temperature.
  4. Take the vehicle for a test drive to verify that the check engine light does not reappear.