my Honda Civic 10th Generation (2016-2021) has a check engine light with code P0420, what should I d...

Solution

1. Preparation

• Tools Required: OBD-II scanner, jack and jack stands, socket set, infrared thermometer.
• Safety Warnings: Disconnect the battery before working on electrical systems and allow the engine to cool before opening the exhaust system.

2. Inspect and Replace Oxygen Sensors

1. Remove the O2 sensor(s) before and after the catalytic converter using a socket set.
2. Inspect the sensors for damage or contamination and replace if necessary.
3. Torque the new sensors to manufacturer's specifications (typically around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

1. Remove the exhaust pipes connected to the catalytic converter, ensuring to loosen all clamps and bolts.
2. Carefully detach the catalytic converter from the exhaust system.
3. Inspect the old catalytic converter for physical damage or blockages.
4. Install the new catalytic converter by reversing the removal steps, ensuring all connections are tight.
5. Torque the bolts to manufacturer's specifications.

4. Clear Codes and Test Drive

1. Reconnect the battery and use the OBD-II scanner to clear any stored codes.
2. Start the engine and let it idle for a few minutes.
3. Take the vehicle for a test drive to ensure the check engine light does not reappear.