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

Solution

1. Preparation

• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use the O2 sensor socket to carefully remove the upstream sensor from the exhaust manifold.
  3. Inspect the sensor for damage or contamination; if damaged, replace it with a new one.
  4. Repeat the removal and inspection process for the downstream sensor.
  5. If either sensor is defective, install the new sensor by threading it in and tightening it to the manufacturer's specified torque (typically 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust hanger tool, torque wrench.
• Sub-steps:
  1. Raise the vehicle using a jack and secure it with jack stands.
  2. Locate the catalytic converter and inspect for physical damage or signs of clogging.
  3. If replacement is needed, remove the exhaust clamps and/or bolts securing the catalytic converter to the exhaust system.
  4. Carefully detach the catalytic converter using an exhaust hanger tool if necessary.
  5. Install the new catalytic converter, ensuring proper alignment, and tighten all bolts to the manufacturer's torque specifications.
  6. Reconnect any exhaust clamps.

4. Finalize the Repair

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Start the engine and allow it to reach operating temperature.
  3. Check for any exhaust leaks around the repaired areas.