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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Using a wrench, carefully disconnect the electrical connectors from the oxygen sensors.
3. Remove the oxygen sensors using an oxygen sensor socket.
4. Install the new oxygen sensors in the reverse order of removal, ensuring they are tightened to manufacturer specifications (typically 30-35 ft-lbs).
5. Reconnect the electrical connectors to the sensors.

3. Check and Replace Catalytic Converter (if necessary)

1. Inspect the catalytic converter for any physical damage or excessive carbon buildup.
2. If replacement is required, remove the exhaust piping connected to the catalytic converter using a socket set.
3. Carefully detach the catalytic converter from its mounting points.
4. Install the new catalytic converter by reversing the removal steps, ensuring all connections are secure.
5. Tighten all exhaust bolts to manufacturer specifications to prevent leaks.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative terminal of the battery.
2. Use the OBD-II scanner to clear any stored trouble codes from the vehicle's computer.
3. Start the engine and allow it to reach operating temperature.