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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, jack and jack stands, exhaust pipe cutter, safety glasses, gloves.
• Ensure the vehicle is parked on a level surface, and the engine is off and cool.

2. Inspect Exhaust System

• Sub-steps:
  1. Lift the vehicle using a jack and secure it with jack stands.
  2. Visually inspect the exhaust system from the engine to the tailpipe for any signs of damage or leaks.
  3. Repair any identified leaks using exhaust tape or replace damaged sections of piping.

3. Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors and use a multimeter to test the voltage output of each sensor.
     • Upstream O2 sensor: Should fluctuate between 0.1V to 0.9V.
     • Downstream O2 sensor: Should remain relatively stable.
  3. Replace any faulty oxygen sensors with new OEM parts.

4. Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. If the catalytic converter is found to be blocked or damaged, proceed to replace it.
  2. Use an exhaust pipe cutter to remove the old catalytic converter, cutting the pipes as necessary.
  3. Install the new catalytic converter, ensuring proper alignment and fitment.
  4. Use a torque wrench to tighten the bolts to the manufacturer's specifications (usually around 30-50 ft-lbs).

5. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery terminals if disconnected.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Conduct a test drive for a minimum of 20 minutes, observing engine performance and monitoring the O2 sensor readings.