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

Solution

1. Preparation

• Gather all 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 during repairs.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Test the sensors with a multimeter to verify proper operation. Replace any faulty sensors.
• Install new oxygen sensors using the torque specifications (typically around 30 ft-lbs).
• Reconnect the battery.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper
• Remove the exhaust pipes connected to the catalytic converter, taking care not to damage any surrounding components.
• Inspect the catalytic converter for damage. If it is clogged or damaged, replace it.
• Install the new catalytic converter, ensuring to use new gaskets and secure all bolts to the manufacturer's torque specifications.
• Reconnect the exhaust pipes.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use the OBD-II scanner to clear any stored codes.
• Start the vehicle and allow it to reach operating temperature.
• Take the vehicle on a test drive to ensure all systems are functioning correctly and check for the reappearance of the P0420 code.