how to fix P0420 code on Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, thermal imaging camera, multimeter.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the vehicle is on a level surface and properly secured with jack stands if lifted.

2. Inspect and Replace Faulty Components

• Oxygen Sensors:

  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors and torque to manufacturer's specifications (typically around 30-40 ft-lbs).
  5. Reconnect the electrical connectors securely.

• Catalytic Converter:

  1. Inspect the catalytic converter for physical damage or clogging.
  2. If replacement is necessary, unbolt the catalytic converter from the exhaust system using a socket set.
  3. Remove any exhaust gaskets or seals and clean the mating surfaces.
  4. Install the new catalytic converter using new gaskets, ensuring all bolts are tightened to the specified torque.
  5. Reconnect any exhaust hangers and support brackets.

3. Clear Codes and Test Drive

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. Take the vehicle for a test drive to ensure the check engine light does not reappear and verify performance.