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

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, safety glasses, gloves.
• Disconnect the negative battery terminal to prevent any electrical shorts during repairs.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use a socket wrench to carefully remove the sensors. Be cautious as they may be hot or stuck.
  3. Apply anti-seize compound to the threads of the new oxygen sensors.
  4. Install the new sensors, ensuring they are securely tightened to the manufacturer’s specifications (usually around 30 Nm or 22 lb-ft).
  5. Reconnect the electrical connectors for the sensors.

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

• Steps:
  1. Remove the exhaust system components as needed to access the catalytic converter, including any heat shields.
  2. Unbolt the catalytic converter using a socket set. Note the position of any gaskets and replace them if damaged.
  3. Install the new catalytic converter, ensuring that all bolts and gaskets are in place.
  4. Torque the bolts to the manufacturer’s specifications.
  5. Reassemble the exhaust system and any heat shields removed during the process.

4. Clear Error Codes and Test Drive

• Steps:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Test drive the vehicle under various conditions (city and highway) to monitor for any reoccurrence of the check engine light.