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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical issues during the repair.
• Raise the vehicle using a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: Oxygen sensor socket, wrench set, multimeter.
• Remove the upstream (pre-catalytic) oxygen sensor using the oxygen sensor socket.
• Test the sensor's voltage output with a multimeter; replace if out of specifications.
• Repeat the process for the downstream (post-catalytic) oxygen sensor if needed.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, penetrating oil, gasket scraper.
• Remove the exhaust pipe bolts connecting to the catalytic converter, applying penetrating oil if necessary.
• Carefully detach the catalytic converter from the exhaust system.
• Inspect the old catalytic converter for signs of clogging or damage; replace if necessary.
• Install the new catalytic converter and secure it with the bolts, tightening to manufacturer specifications (usually around 25-30 ft-lbs).
• Replace any gaskets as needed to prevent exhaust leaks.

4. Reset the Engine Control Unit (ECU)

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the ECU.
• Start the vehicle and allow it to reach operating temperature.