how to fix P0420 code on Honda Pilot YF3 (2016-2022)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical issues during repairs.
• Raise the vehicle securely on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Check the upstream and downstream oxygen sensor connections for corrosion or damage.
• If faulty, replace the upstream oxygen sensor first:
  • Remove the electrical connector from the sensor.
  • Use an O2 sensor socket to unscrew the sensor from the exhaust pipe.
  • Apply anti-seize compound to the threads of the new sensor.
  • Install and torque to manufacturer specifications (typically around 30 ft-lbs).
  • Reconnect the electrical connector.
• Repeat for the downstream sensor if needed.

3. Inspect Catalytic Converter

• Tools Required: Wrench set, pry bar
• Check for physical damage or excessive rust on the catalytic converter.
• If damaged, proceed to replace the catalytic converter:
  • Remove the exhaust pipes connected to the catalytic converter, noting any gaskets or bolts.
  • Use a pry bar if needed to break any carbon buildup.
  • Install the new catalytic converter using new gaskets and torque to manufacturer specifications (typically around 40 ft-lbs for flange bolts).
  • Reattach exhaust pipes.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and let it reach operating temperature.
• Conduct a test drive to ensure the check engine light does not reappear.