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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and secure it with wheel chocks.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Oxygen Sensors

1. Locate the Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the Sensors: Use an oxygen sensor socket to unscrew and remove both sensors. Inspect the wiring for damage.
3. Install New Sensors: Apply anti-seize compound to the threads of the new sensors and install them, ensuring they are properly tightened (typically 30 Nm or 22 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components: If the catalytic converter is faulty, it may need to be replaced. Use a socket set to remove any bolts securing the exhaust components (flanges, hangers).
2. Install New Catalytic Converter: Position the new catalytic converter in place, ensuring proper alignment with the exhaust system. Secure it using the original bolts (torque to manufacturer specifications).

4. Reconnect Battery and Clear Codes

1. Reconnect the battery terminal and ensure it is securely fastened.
2. Use the OBD-II scanner to clear the P0420 code from the ECU.

5. Test Drive

• Take the vehicle for a test drive under various conditions to ensure the check engine light does not reappear and the vehicle operates normally.