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

• Tools Required: O2 sensor socket, ratchet, torque wrench, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use the O2 sensor socket to carefully unscrew the faulty sensor.
  3. Install the new oxygen sensor by threading it in by hand, then use the torque wrench to tighten it to the manufacturer’s specifications (typically around 30-40 lb-ft).
  4. Reconnect the electrical connector to the new sensor.

3. Check and Replace Catalytic Converter (if necessary)

• Tools Required: Jack and jack stands, socket set, exhaust hanger removal tool.
• Sub-steps:
  1. Safely lift the vehicle using a jack and secure it with jack stands.
  2. Remove any heat shields and other components obstructing access to the catalytic converter.
  3. Use the socket set to unbolt the catalytic converter from the exhaust system.
  4. Inspect the catalytic converter for damage and blockage; if defective, replace it with a new unit.
  5. Install the new catalytic converter by reversing the removal steps, ensuring all bolts are tightened to the specified torque.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle's memory.
  3. Start the engine and let it reach operating temperature.
  4. Take the vehicle for a test drive, monitoring for any reoccurrence of the check engine light.