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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, infrared thermometer, jack and jack stands.
• Gather replacement parts as needed, including oxygen sensors or catalytic converter if faulty.
• Disconnect the battery to ensure safety while working on the electrical systems.

2. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors before and after the catalytic converter.
2. Remove the electrical connectors from the sensors.
3. Use a wrench to unscrew the sensors from the exhaust pipes.
4. Install the new oxygen sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Screw the sensors into place and torque to manufacturer specifications (usually around 30 lb-ft).
5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Raise the vehicle using a jack and secure it with jack stands.
2. Remove the exhaust pipes attached to the catalytic converter using a socket set.
3. Carefully detach the old catalytic converter from the exhaust system.
4. Install the new catalytic converter:
   • Ensure all gaskets are in good condition or replace them if needed.
   • Align the new converter with the exhaust pipes and secure it with the bolts, tightening to the specified torque (usually around 25 lb-ft).
5. Reconnect all exhaust components and ensure there are no leaks.

4. Clear Codes and Test

1. Reconnect the battery.
2. Use the OBD-II scanner to clear any diagnostic trouble codes.
3. Start the engine and allow it to reach operating temperature.
4. Take the vehicle for a test drive to monitor the performance and check for returning codes.