how to fix P0420 code in my Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Use a socket wrench to carefully remove the oxygen sensors from their positions.
3. Inspect the sensors for damage or excessive carbon buildup.
4. If faulty, replace with new OEM or high-quality aftermarket oxygen sensors, ensuring they are properly torqued (typically around 30 ft-lbs).
5. Reconnect the electrical connectors securely.

3. Replace the Catalytic Converter (if necessary)

1. Raise the vehicle securely using jack stands.
2. Locate the catalytic converter in the exhaust system.
3. Remove any heat shields and brackets holding the converter in place.
4. Use a wrench to disconnect the exhaust flanges at both ends of the converter.
5. Remove the old catalytic converter and install the new one, ensuring correct alignment.
6. Reattach all brackets and heat shields, tightening bolts to the manufacturer's specifications (typically around 25-30 ft-lbs for exhaust components).

4. Clear Codes and Test Drive

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code from the system.
3. Take the vehicle for a test drive to ensure the check engine light does not reappear and monitor engine performance.