how to fix Honda Civic 11th Generation (2022-Present) check engine light P0420

Solution

1. Preparation

• Gather tools and parts required for repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter.
• Use the multimeter to test the pre-catalytic converter oxygen sensor for proper voltage output (typically between 0.1V and 0.9V).
• If the readings are out of spec, remove the old sensor using the O2 sensor socket and install a new one. Torque to manufacturer specifications (usually around 30 lb-ft).
• Repeat the procedure for the post-catalytic converter oxygen sensor if found to be faulty.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Visually inspect the catalytic converter for signs of damage or clogging.
• If replacement is needed, disconnect the exhaust pipes and oxygen sensors from the catalytic converter.
• Remove the old converter and install the new one, ensuring proper alignment.
• Torque the exhaust connections to the manufacturer specifications.

4. Reset the Engine Control Module (ECM)

• Reconnect the battery and start the engine.
• Use the OBD-II scanner to clear the P0420 code from the ECM.
• Allow the vehicle to run for a few minutes to ensure the system recalibrates.