how to fix P0420 code on Honda Pilot YF4 (2023-Present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and engage the parking brake.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Remove Oxygen Sensors

• Tools Required: Oxygen sensor socket, ratchet, and extensions.
• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors on the exhaust system.
• Use the oxygen sensor socket to carefully unscrew both sensors from their respective locations.
• Set them aside for inspection.

3. Inspect and Clean

• Inspect the oxygen sensors for any signs of contamination, such as soot or oil residue.
• If contamination is present, use a suitable sensor-safe cleaner to carefully clean the sensors. Avoid harsh chemicals that might damage them.

4. Replace Catalytic Converter (if faulty)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary).
• Disconnect the exhaust pipe before and after the catalytic converter, ensuring all mounting bolts are removed.
• Remove the old catalytic converter from the vehicle.
• Install the new catalytic converter, ensuring proper alignment and fitment.
• Torque all bolts to the manufacturer's specifications (refer to service manual for exact values).

5. Reinstall Oxygen Sensors

• Reinstall the upstream and downstream oxygen sensors, ensuring they are tightened to the correct specifications.
• Reconnect the battery terminal.

6. Test the System

• Start the engine and let it reach operating temperature.
• Use an OBD-II scanner to clear the P0420 code and monitor for any reoccurrences.
• Perform a test drive to ensure the vehicle operates smoothly without the check engine light returning.