how to fix P0420 error code in 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.
• Raise the vehicle using jack stands to access the exhaust system safely.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Remove the upstream oxygen sensor first:
  1. Locate the upstream O2 sensor (before the catalytic converter).
  2. Use an O2 sensor socket to unscrew the sensor.
  3. Disconnect the electrical connector.
• Install the new upstream oxygen sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Screw the sensor into place and connect the electrical connector.
• Repeat the process for the downstream oxygen sensor (after the catalytic converter) if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), gasket scraper
• Remove the old catalytic converter:
  1. Locate the mounting bolts securing the catalytic converter to the exhaust pipes.
  2. Use a socket set to remove the bolts and detach the converter.
  3. If necessary, cut the exhaust pipes with an exhaust pipe cutter.
• Install the new catalytic converter:
  1. Ensure the mounting surfaces are clean and free of old gasket material.
  2. Position the new catalytic converter and secure it with the mounting bolts, applying the specified torque (typically 30-40 ft-lbs).
  3. Replace any gaskets or clamps as needed to ensure a proper seal.

4. Reconnect Battery and Clear Codes

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