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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Inspect the oxygen sensors for corrosion or damage.
• Remove the pre-catalytic and post-catalytic oxygen sensors using the O2 sensor socket.
• Install new oxygen sensors:
  • Apply anti-seize compound to the threads (if required).
  • Torque to manufacturer's specification (usually around 30-40 lb-ft).

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket, penetrating oil
• Remove any heat shields or brackets that may obstruct access to the catalytic converter.
• Disconnect the exhaust pipes from the catalytic converter using the socket set.
• Remove the catalytic converter, noting the orientation for installation of the new unit.
• Install the new catalytic converter:
  • Ensure gasket surfaces are clean.
  • Install the new exhaust gasket.
  • Reattach the exhaust pipes and torque fasteners to specification (usually around 20-30 lb-ft).

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the ECM.

5. Final Check

• Start the engine and let it idle for a few minutes.
• Observe for any exhaust leaks or unusual noises.
• Conduct a test drive to ensure the check engine light does not reappear.