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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace O2 Sensors (if faulty)

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
  2. Use a socket wrench to remove the faulty O2 sensor(s).
  3. Apply anti-seize compound to the threads of the new O2 sensor(s).
  4. Install the new O2 sensor(s) and tighten to manufacturer's specifications (usually around 30 ft-lbs).
• Tools Required: O2 sensor socket, torque wrench.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Remove the exhaust pipe connected to the catalytic converter using a socket wrench.
  2. Unbolt the catalytic converter from the exhaust manifold or flange.
  3. Clean the mating surfaces to ensure a good seal for the new converter.
  4. Install the new catalytic converter and torque the bolts to manufacturer's specifications (usually around 30-40 ft-lbs).
  5. Reattach the exhaust pipe and ensure all connections are secure.
• Tools Required: Socket set, torque wrench.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the vehicle and allow it to reach normal operating temperature.
  4. Perform a test drive to ensure the check engine light does not reappear.
• Tools Required: OBD-II scanner.