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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent any electrical shorts.
• Allow engine components to cool before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, socket set, torque wrench.
• Remove the downstream (post-catalytic) oxygen sensor.
• Inspect the sensor for damage or contamination.
• If faulty, replace with a new OEM or quality aftermarket sensor. Torque to specifications (typically around 30 lb-ft).
• Repeat the same process for the upstream (pre-catalytic) oxygen sensor if necessary.

3. Inspect and Replace Catalytic Converter

• Tools Required: Cutting torch or reciprocating saw, socket set, gaskets, torque wrench.
• Remove any heat shields covering the catalytic converter.
• Disconnect the exhaust pipes from the catalytic converter and remove the bolts holding it in place.
• Inspect the catalytic converter for internal damage or clogging.
• Replace with a new catalytic converter and install using new gaskets. Torque bolts to the manufacturer's specifications (usually around 30-40 lb-ft).
• Reinstall any heat shields removed during the process.

4. Clear Codes and Test Drive

• Reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Test drive the vehicle under various driving conditions to ensure the check engine light does not reappear.