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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and engage the parking brake.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Disconnect the negative battery terminal.
  2. Locate the upstream and downstream oxygen sensors.
  3. Use the O2 sensor socket to remove the sensors.
  4. Inspect the wiring and connectors for damage; replace if necessary.
  5. Install new oxygen sensors, torque to manufacturer's specifications (typically around 30 lb-ft).
  6. Reconnect the negative battery terminal.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), gasket scraper
• Sub-steps:
  1. Raise the vehicle safely using jack stands.
  2. Remove the exhaust pipe bolts securing the catalytic converter.
  3. Cut the exhaust pipe if necessary to remove the old catalytic converter.
  4. Clean the mounting surfaces on the exhaust system.
  5. Install the new catalytic converter with new gaskets, tightening bolts to the manufacturer's specifications (typically around 25-30 lb-ft).
  6. Reconnect any oxygen sensors if they were removed.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Use the OBD-II scanner to clear the P0420 code.
  2. Start the engine and let it idle for a few minutes.
  3. Take the vehicle for a test drive, monitoring engine performance and checking for the return of the check engine light.