how to fix P0420 code on my 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 shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for contamination or damage; replace if necessary.
• Install new sensors and torque them to the manufacturer’s specifications (typically around 33 ft-lbs).

3. Inspect and Repair Exhaust System

• Tools Required: Socket set, exhaust pipe cutter (if necessary), welding equipment (if welding is required).
• Visually inspect the exhaust system for any cracks, holes, or loose connections.
• Repair or replace any damaged components such as exhaust pipes or gaskets.
• If necessary, replace the catalytic converter following removal of the old unit.

4. Reset the OBD-II System

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the system.

5. Test Drive

• Take the vehicle for a test drive to monitor for any reoccurrence of the check engine light.