how to fix P0420 code on Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather necessary tools and equipment.
• Ensure the vehicle is on a level surface and securely raise it using jack stands.
• Disconnect the battery to prevent electrical shorts.

2. Oxygen Sensor Replacement (if faulty)

1. Locate the upstream and downstream oxygen sensors.
2. Use an O2 sensor socket to unscrew the faulty sensor from the exhaust pipe.
3. Apply anti-seize compound to the threads of the new sensor.
4. Screw the new oxygen sensor into place and tighten to manufacturer specifications (typically around 30 ft-lbs).
5. Reconnect the electrical connector to the new sensor.

3. Catalytic Converter Inspection/Replacement

1. Inspect the catalytic converter for any physical damage, such as dents or rust.
2. If damaged, remove the bolts or clamps securing the catalytic converter to the exhaust system.
3. Carefully detach the old catalytic converter and replace it with a new one.
4. Reinstall and tighten the bolts or clamps to manufacturer specifications.
5. Ensure all gaskets are in good condition and replace if necessary.

4. Clear the Error Codes

1. Reconnect the battery terminal.
2. Use the OBD-II scanner to clear the P0420 code.
3. Start the engine and allow it to reach operating temperature.