how to fix P0420 code on Honda Pilot YF4 (2023-Present)

Solution

1. Preparation

• Gather necessary tools and safety equipment.
• Disconnect the battery to avoid electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Use the O2 sensor socket to carefully remove the upstream sensor.
  3. Inspect the sensor for carbon buildup or damage. Replace if faulty.
  4. Repeat for the downstream sensor.
  5. Install new sensors and torque to manufacturer specifications (usually around 30 ft-lbs).

3. Inspect and Test Catalytic Converter

• Tools Required: Torque wrench, exhaust pressure gauge (if available).
• Sub-steps:
  1. Inspect the catalytic converter for physical damage or signs of clogging.
  2. If equipped, connect an exhaust pressure gauge to monitor back pressure.
  3. If back pressure exceeds manufacturer specifications (typically above 2.5 psi at full throttle), consider replacing the catalytic converter.
  4. Remove the exhaust manifold or exhaust pipe as necessary to replace the catalytic converter.
  5. Install the new catalytic converter, ensuring all gaskets and seals are in good condition.
  6. Torque all bolts to manufacturer specifications.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Test drive the vehicle for at least 20 minutes while monitoring engine performance.