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

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Check the voltage output of the upstream and downstream O2 sensors. If the downstream sensor is not showing normal values (0.1-0.9V), it may need replacement.
• If faulty, remove the sensor with an O2 sensor socket and install a new one.
• Torque the new sensor to the manufacturer’s specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Jack and jack stands, exhaust pipe cutter, socket set, torque wrench
• Inspect the catalytic converter for signs of clogging or damage. If necessary, remove it by cutting the pipes or unbolting the flanges.
• Install a new catalytic converter, ensuring proper alignment with the exhaust system.
• Torque all bolts to factory specifications (check service manual for specific values).

4. Clear Error Codes

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
• Start the engine and allow it to run for a few minutes to check for any return of the check engine light.