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

Solution

1. Preparation

• Gather tools required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench, multimeter.
• Remove the upstream oxygen sensor by disconnecting the electrical connector and unscrewing it.
• Install the new upstream oxygen sensor and reconnect the electrical connector.
• Repeat the process for the downstream oxygen sensor if testing indicates a failure.

3. Check and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, cutting torch (if necessary).
• Raise the vehicle and secure it with jack stands.
• Remove the bolts securing the catalytic converter to the exhaust system.
• If the converter is damaged or clogged, remove it from the exhaust system.
• Install the new catalytic converter, ensuring proper alignment with exhaust flanges.
• Torque the bolts to the manufacturer's specifications.

4. Reset the Engine Control Module (ECM)

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