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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• If the oxygen sensors are faulty:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Apply penetrating oil to the sensor threads and allow it to soak.
  3. Using an O2 sensor socket, carefully remove the faulty sensors.
  4. Install new sensors by following the manufacturer's torque specifications (typically around 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• If the catalytic converter is determined to be inefficient:
  1. Remove any heat shields or brackets securing the catalytic converter using the socket set.
  2. Cut the exhaust pipes if necessary to remove the catalytic converter.
  3. Install the new catalytic converter, ensuring the exhaust gaskets are in good condition.
  4. Torque all bolts to the manufacturer’s specifications (check service manual for specific values).

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals ensuring they are secure.
• Use an OBD-II scanner to clear the P0420 code from the system.