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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors. Generally, the upstream sensor is before the catalytic converter, and the downstream is after it.
  2. Use the O2 sensor socket to carefully remove the upstream oxygen sensor.
  3. Inspect the sensor for damage or carbon buildup. If corroded or damaged, replace it with a new sensor.
  4. Repeat the process for the downstream oxygen sensor. Ensure the new sensor is properly threaded and tightened to the manufacturer's specifications (typically around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Jack and jack stands, socket set, exhaust pipe cutter (if necessary), new gaskets.
• Sub-steps:
  1. Safely lift the vehicle using a jack and secure it with jack stands.
  2. Locate the catalytic converter and inspect for physical damage and carbon buildup.
  3. If the converter is damaged or clogged, disconnect the exhaust pipes from the catalytic converter using the socket set. Use an exhaust pipe cutter if necessary.
  4. Remove the old catalytic converter and clean the surrounding exhaust flange.
  5. Install the new catalytic converter, ensuring to use new gaskets to prevent leaks.
  6. Reconnect the exhaust system and tighten all bolts to the recommended torque specifications.

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery.
• Use the OBD-II scanner to clear the P0420 code and reset the check engine light.