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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal.
• Allow the exhaust system to cool down to avoid burns.

2. Replace Oxygen Sensors

• Remove the oxygen sensor wiring harness connector.
• Use an oxygen sensor socket to unscrew the old oxygen sensors (both upstream and downstream).
• Apply anti-seize compound to the threads of the new sensors.
• Install the new sensors and reconnect the wiring harness.

3. Inspect and Replace Catalytic Converter (if necessary)

• Use a jack and jack stands to lift the vehicle safely.
• Remove the exhaust pipes connected to the catalytic converter using a socket set.
• Detach any heat shields or brackets holding the catalytic converter in place.
• Inspect the condition of the catalytic converter; if damaged or clogged, remove it.
• Install the new catalytic converter, ensuring all gaskets are replaced and properly aligned.
• Reattach the exhaust pipes and tighten the bolts to the manufacturer’s specifications.

4. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Test drive the vehicle to ensure the check engine light does not reappear and monitor performance.