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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-cat) and downstream (post-cat) oxygen sensors.
  2. Using the O2 sensor socket, remove the upstream sensor first.
  3. Install the new O2 sensor and torque to the manufacturer's specifications (usually around 30 lb-ft).
  4. Repeat the process for the downstream sensor.

3. Test and Replace Catalytic Converter (if necessary)

• Tools Required: Wrench set, jack and jack stands, exhaust pipe cutter.
• Sub-steps:
  1. Raise the vehicle and secure it with jack stands.
  2. Remove the exhaust bolts connecting the catalytic converter to the exhaust pipe using the wrench.
  3. Cut the exhaust pipe if needed for easier removal of the catalytic converter.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque the exhaust bolts to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the battery terminals.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.