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

Solution

1. Preparation

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

2. Inspect Exhaust System

• Examine the exhaust pipes and connections for leaks.
• Use a flashlight to check for any rust or holes in the exhaust system.
• Repair or replace any damaged sections as necessary.

3. Oxygen Sensor Replacement

• Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Disconnect the electrical connectors from both sensors.
• Use an O2 sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
• Install new oxygen sensors and torque to the manufacturer's specifications (usually around 30 ft-lbs).
• Reconnect the electrical connectors.

4. Catalytic Converter Inspection/Replacement

• If the catalytic converter is damaged or clogged, remove it by loosening the bolts securing it to the exhaust system.
• Replace with a new catalytic converter that meets OEM specifications.
• Ensure all gaskets are replaced to prevent exhaust leaks and torque bolts to manufacturer specifications.

5. Reset the OBD-II System

• Reconnect the battery and use an OBD-II scanner to clear the P0420 code.
• Perform a test drive to confirm that the check engine light does not return.