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 shock.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors along the exhaust system.
  2. Using a wrench, carefully remove the defective oxygen sensors.
  3. Install new oxygen sensors, ensuring they are tightened to the manufacturer’s specifications (typically around 30 ft-lbs).
• Tools Required: Oxygen sensor socket, wrench, torque wrench.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  1. Remove the exhaust heat shield if applicable.
  2. Unbolt the catalytic converter from the exhaust manifold and the exhaust pipe using a socket set.
  3. Inspect the gaskets and replace them if damaged.
  4. Install the new catalytic converter, ensuring all bolts are tightened to manufacturer specifications (typically around 25-30 ft-lbs).
• Tools Required: Socket set, torque wrench, exhaust gasket.

4. Clear Codes and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code.
  3. Start the engine and let it run until it reaches operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not re-illuminate.
• Tools Required: OBD-II scanner.