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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Inspect and Replace Oxygen Sensors

1. Locate Sensors: Find the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Disconnect Sensors: Carefully unplug the electrical connectors from both sensors.
3. Remove Sensors: Use an oxygen sensor socket to remove the sensors from their respective locations.
4. Install New Sensors: Apply anti-seize compound to the threads of the new sensors. Install them in the same location, ensuring they are tightened to manufacturer specifications (typically 30-40 ft-lbs).
5. Reconnect Connectors: Plug the electrical connectors back into the new sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components: Use a socket set to unbolt the exhaust pipe connections to access the catalytic converter.
2. Inspect Catalytic Converter: Check for physical damage, signs of overheating, or blockages in the converter.
3. Install New Catalytic Converter: Position the new catalytic converter in place and secure it with bolts. Ensure all gaskets are replaced to prevent leaks.
4. Reconnect Exhaust System: Reattach any exhaust pipes that were disconnected and tighten to the specified torque.

4. Clear Codes and Test Drive

1. Reconnect Battery: Reconnect the battery terminals.
2. Clear Error Codes: Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
3. Test Drive: Take the vehicle for a test drive to ensure the check engine light does not reappear and that performance issues are resolved.