how to fix P0420 code on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool before starting work.

2. Oxygen Sensor Replacement (if necessary)

1. Locate the Oxygen Sensors
   • Identify the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Remove the Old Sensor
   • Use an oxygen sensor socket and ratchet to unscrew the sensor from its mounting.
   • Disconnect the electrical connector.
3. Install the New Sensor
   • Apply anti-seize compound to the threads of the new oxygen sensor (if not pre-applied).
   • Screw the new sensor into place and tighten to manufacturer specifications (typically around 30 lb-ft).
   • Reconnect the electrical connector.

3. Catalytic Converter Inspection/Replacement (if necessary)

1. Inspect the Catalytic Converter
   • Visually check for any signs of physical damage or rattling.
   • If damaged, proceed to replacement.
2. Remove the Old Catalytic Converter
   • Loosen and remove the bolts or nuts securing the catalytic converter to the exhaust system using a socket set.
   • Carefully remove the catalytic converter from the exhaust system.
3. Install the New Catalytic Converter
   • Position the new catalytic converter in place.
   • Secure it with the bolts or nuts, tightening to manufacturer specifications (usually between 20-30 lb-ft).
   • Ensure all gaskets are replaced to prevent leaks.

4. Clear the Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory.

5. Test Drive

• Start the engine and allow it to reach normal operating temperature.
• Take the vehicle for a test drive to ensure that all systems are functioning correctly and the check engine light does not reappear.