how to diagnose P0420 code in my Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather required tools and parts.
• Ensure the vehicle is parked on a flat surface and the ignition is off.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, socket set, torque wrench.
• Remove the upstream (pre-catalytic) O2 sensor:
  • Locate the sensor on the exhaust manifold or front pipe.
  • Use the O2 sensor socket to unscrew the sensor.
  • Inspect the sensor for carbon buildup or damage.
• Install the new O2 sensor:
  • Apply anti-seize compound to the threads of the new sensor.
  • Torque the sensor 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 hanger removal tool.
• Raise the vehicle and secure it with jack stands.
• Remove the exhaust pipes connected to the catalytic converter by:
  • Detaching exhaust clamps and hangers.
  • Using a socket set to remove bolted connections.
• Inspect the catalytic converter for internal damage or blockage.
• Replace with a new catalytic converter:
  • Ensure proper alignment with exhaust pipes.
  • Torque all bolts to manufacturer's specifications (typically around 25 lb-ft).

4. Clear Codes and Test Drive

• Reconnect the battery and clear any stored codes using the OBD-II scanner.
• Start the engine and allow it to reach operating temperature.
• Perform a test drive to ensure the vehicle runs smoothly and the check engine light does not reappear.