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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• If the upstream or downstream oxygen sensors are faulty:
  1. Locate the O2 sensors (usually on the exhaust manifold and downstream of the catalytic converter).
  2. Disconnect the electrical connectors from the sensors.
  3. Use an O2 sensor socket to unscrew the faulty sensor(s).
  4. Install the new sensor(s), ensuring they are tightened to the manufacturer’s specified torque (usually around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• If the catalytic converter is found to be damaged or inefficient:
  1. Locate the catalytic converter and determine how it is connected to the exhaust system (bolted or welded).
  2. If bolted, remove the bolts using the socket set; if welded, carefully cut the exhaust pipe using an exhaust pipe cutter.
  3. Install the new catalytic converter, ensuring to align it properly with the exhaust system.
  4. Tighten the bolts to the manufacturer's specified torque (usually around 25 lb-ft).
  5. Reconnect any sensors or components that were disconnected.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner
• After repairs are complete:
  1. Reconnect the vehicle's battery.
  2. Use an OBD-II scanner to clear any stored codes.
  3. Start the engine and allow it to warm up.
  4. Conduct a test drive to monitor the operation of the vehicle.