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 battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

1. Locate Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove Sensors:
   • Use an oxygen sensor socket to carefully unscrew the sensors.
   • Disconnect the wiring harness from each sensor.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors in reverse order of removal, ensuring they are securely tightened to manufacturer specifications (typically 30-40 lb-ft).
4. Reconnect Wiring: Ensure all electrical connections are secure.

3. Examine and Replace Catalytic Converter (if necessary)

1. Inspect Catalytic Converter: Look for signs of damage or obstruction. If the converter is damaged or clogged, it must be replaced.
2. Remove Old Catalytic Converter:
   • Use a socket set to unbolt the catalytic converter from the exhaust manifold and the exhaust pipe.
   • Remove any mounting brackets or heat shields as necessary.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place and secure it with the original bolts and brackets.
   • Torque bolts to manufacturer specifications (typically around 30 lb-ft).
4. Reassemble Any Removed Components: Ensure all heat shields and exhaust components are correctly reattached.

4. Final Steps

1. Reconnect Battery: Reconnect the battery terminals.
2. Clear Error Codes: Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
3. Test Drive: Drive the vehicle for a sufficient distance to allow the ECU to recheck the catalytic converter's efficiency.