how to fix P0420 code on Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench, penetrating oil.
  • a. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • b. Disconnect the wiring harness from each oxygen sensor.
  • c. Apply penetrating oil to the sensor threads and allow it to sit for a few minutes.
  • d. Use the O2 sensor socket to remove the upstream sensor. Replace it with a new sensor and torque to manufacturer specifications (typically 30 ft-lbs).
  • e. Repeat the process for the downstream sensor if it shows abnormal readings.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket, safety goggles, jack stands.
  • a. Raise the vehicle securely on jack stands.
  • b. Unbolt the catalytic converter from the exhaust system, taking care to retain any gaskets for reuse or replace if damaged.
  • c. Inspect the catalytic converter for blockages or significant wear.
  • d. Install a new catalytic converter, ensuring proper alignment and bolting it to the exhaust system.
  • e. Torque the bolts to the manufacturer's specifications (typically 30-40 ft-lbs).

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
  • a. Reconnect the negative battery terminal.
  • b. Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
  • c. Start the engine and conduct a test drive to allow the vehicle to enter closed-loop operation.