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

Solution

1. Preparation

• Gather tools and parts, ensuring the vehicle is parked on a level surface.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Unplug the electrical connectors from each sensor.
  3. Use the O2 sensor socket to remove the faulty oxygen sensors.
  4. Install new oxygen sensors, ensuring they are tightened to manufacturer specifications (typically 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, torque wrench.
• Sub-steps:
  1. Raise the vehicle securely on jack stands.
  2. Remove any heat shields or brackets securing the catalytic converter.
  3. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe using the socket set.
  4. Inspect the catalytic converter for blockages or damage; replace if necessary.
  5. Install the new catalytic converter, ensuring proper alignment and torque all bolts to manufacturer specifications (typically 40-50 ft-lbs).
  6. Reattach any heat shields or brackets removed earlier.

4. Clear Codes and Test

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and let it run for a few minutes to check if the code reappears.