how to fix Honda Pilot Third Generation (2016-present) check engine light P0420

Solution

1. Preparation

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

2. Oxygen Sensor Inspection

• Tools Required: Multimeter
• Sub-steps:
  1. Locate the upstream oxygen sensor (pre-catalytic converter).
  2. Disconnect the sensor wiring harness.
  3. Set the multimeter to voltage mode and connect it to the sensor terminals.
  4. Start the engine and monitor the voltage; it should fluctuate between 0.1V and 0.9V.
  5. If the readings are outside this range, replace the sensor.

3. Catalytic Converter Inspection and Replacement

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed)
• Sub-steps:
  1. Raise the vehicle safely using jack stands and remove the underbody cover if necessary.
  2. Inspect the catalytic converter for physical damage, such as dents or cracks.
  3. If damaged, unbolt the catalytic converter from the exhaust system using the socket set.
  4. If needed, cut the exhaust pipe to remove the old converter.
  5. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  6. Torque the bolts to the manufacturer's specifications (typically around 30-35 lb-ft).

4. Reconnect Oxygen Sensors

• Reattach the upstream and downstream oxygen sensors to their respective connectors.
• Ensure that the wiring harness is secured and free from contact with hot surfaces.

5. Reconnect Battery

• Reconnect the negative battery terminal and ensure it is tight and secure.

6. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.