how to fix P0420 code in Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and engage the parking brake.
• Disconnect the battery before beginning work, especially when dealing with electrical components.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Remove the O2 sensors using the O2 sensor socket; be cautious of the potential for rust or corrosion.
  4. Install the new O2 sensors and torque them to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

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

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed).
• Sub-steps:
  1. Inspect the catalytic converter visually for any physical damage or blockage.
  2. If replacement is necessary, remove the exhaust components leading to the catalytic converter (if applicable).
  3. Unbolt the catalytic converter from the exhaust system using the socket set; note the mounting positions for reinstallation.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque the bolts to the manufacturer's specifications (typically around 30 ft-lbs).

4. Clear the 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 from the vehicle's memory.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Perform a test drive to monitor engine performance and ensure the check engine light does not reappear.