how to fix P0420 code on Honda Pilot Third Generation (2016-present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually near the exhaust manifold and after the catalytic converter).
  2. Apply penetrating oil to the threads of the oxygen sensors to ease removal.
  3. Disconnect the electrical connectors from the oxygen sensors.
  4. Use the O2 sensor socket to remove the sensors from the exhaust system.
  5. Install the new sensors by threading them in by hand and tightening them to the manufacturer’s specified torque (typically around 30 lb-ft).
  6. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust gasket, pry bar
• Sub-steps:
  1. Safely raise the vehicle using a jack and secure it with jack stands.
  2. Inspect the catalytic converter for any signs of damage or blockage.
  3. If replacement is needed, disconnect the exhaust pipe from the catalytic converter using a socket set.
  4. Remove any mounting bolts and brackets securing the catalytic converter to the exhaust system.
  5. Install the new catalytic converter, ensuring a proper fit and alignment.
  6. Torque the mounting bolts to the specified value (consult your vehicle manual for exact numbers).
  7. Reconnect the exhaust pipe and ensure there are no leaks.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive, monitoring performance and ensuring the check engine light does not reappear.