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

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use the O2 sensor socket to remove the upstream oxygen sensor from the exhaust manifold.
  3. Install a new oxygen sensor, ensuring it is properly threaded and tightened to the manufacturer's torque specifications (usually around 30 lb-ft).
  4. Repeat for the downstream oxygen sensor if found defective.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack stands, exhaust hanger removal tool.
• Sub-steps:
  1. Raise the vehicle and support it securely with jack stands.
  2. Remove the exhaust pipes connected to the catalytic converter, using a socket set.
  3. Remove any exhaust hangers securing the catalytic converter to the vehicle.
  4. Install the new catalytic converter in reverse order of removal, ensuring all bolts are tightened to the manufacturer's specifications.
  5. Reconnect exhaust pipes and hangers securely.

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 ECU.
  3. Start the vehicle and conduct a test drive to ensure the check engine light does not reappear.