how to diagnose Honda Pilot YF3 (2016-2022) P0420 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repairs.
• Allow the engine to cool completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Remove the upstream (pre-catalytic) oxygen sensor by applying penetrating oil if necessary and using the O2 sensor socket.
• Install the new oxygen sensor, tightening to the manufacturer’s specified torque (typically around 30 Nm or 22 lb-ft).
• Repeat the process for the downstream (post-catalytic) oxygen sensor.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter, gaskets.
• Unbolt the exhaust pipes leading to and from the catalytic converter using the socket set.
• Cut the exhaust pipes if necessary to remove the old catalytic converter.
• Install the new catalytic converter with new gaskets, ensuring all bolts are tightened to the manufacturer’s specified torque.
• Reconnect the exhaust pipes and ensure there are no leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery terminals securely.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory.