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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set
• Remove the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
• Inspect the sensors for contamination. If they are fouled or malfunctioning, replace them with OEM sensors.
• Reinstall the new sensors and reconnect the wiring harness.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket set
• Remove any heat shields or brackets securing the catalytic converter.
• Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
• Inspect the exhaust gaskets and replace if damaged.
• Install the new catalytic converter, ensuring proper alignment and torque specifications (typically 30-40 ft-lbs).
• Reattach any heat shields or brackets.

4. Reset the ECM

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code from the ECM.
• Ensure all connections are secure and components are properly installed.