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

Solution

1. Preparation

• Disconnect the battery to prevent electrical shorts while working on the vehicle.
• Gather tools and parts required for the repair.

2. Replace Faulty O2 Sensors

1. Locate the O2 Sensors: Identify the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
2. Remove the Sensors:
   • Use an O2 sensor socket to carefully unscrew the upstream sensor.
   • Repeat for the downstream sensor if it is also faulty.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new O2 sensors.
   • Install the upstream sensor first, then the downstream sensor, ensuring they are tightened to the manufacturer's specifications (typically around 30 ft-lbs).
4. Reconnect Wiring: Plug in the electrical connectors to the new sensors.

3. Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components:
   • Loosen and remove any bolts securing the catalytic converter to the exhaust system using a socket set.
   • Carefully detach the catalytic converter from the exhaust system.
2. Install New Catalytic Converter:
   • Position the new catalytic converter in place.
   • Secure it with the bolts, tightening to the manufacturer's specifications.
3. Reconnect Exhaust System: Ensure all joints are sealed properly and reattach any heat shields.

4. Clear Codes and Test

1. Reconnect Battery: Reconnect the battery terminals.
2. Clear the Codes: Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Test Drive: Take the vehicle for a test drive to ensure that the check engine light does not reappear.