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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely before beginning.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench

• Remove the front (upstream) oxygen sensor:

  1. Locate the sensor on the exhaust manifold.
  2. Use an O2 sensor socket to unscrew the sensor.
  3. Install the new oxygen sensor and torque it to the manufacturer's specifications (generally around 30 ft-lbs).

• Remove the rear (downstream) oxygen sensor:

  1. Locate the sensor after the catalytic converter.
  2. Unscrew it using the O2 sensor socket.
  3. Install the new sensor and torque it to the specified value.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool
• If the oxygen sensors are functioning properly, inspect the catalytic converter:
  1. Check for physical damage, rust, or signs of blockage.
  2. If defective, unbolt the catalytic converter from the exhaust system.
  3. Replace it with a new catalytic converter, ensuring it is compatible with the 2016-present Honda Pilot.
  4. Reinstall and torque bolts to specified values (usually around 30-40 ft-lbs).

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use an OBD-II scanner to clear the P0420 code from the system.