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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid any electrical issues during repair.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use the O2 sensor socket to unscrew the upstream oxygen sensor.
  3. Install the new oxygen sensor, ensuring it is torqued to the manufacturer's specifications (typically around 30-40 ft-lb).
  4. Repeat for the downstream oxygen sensor if it was found faulty during diagnostics.

3. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, wrench set, torque wrench, exhaust sealant.
• Sub-steps:
  1. Remove the exhaust pipe connected to the catalytic converter using a socket set.
  2. Detach any mounting brackets securing the catalytic converter.
  3. Remove the old catalytic converter from the exhaust system.
  4. Install the new catalytic converter, aligning it properly with exhaust pipes and brackets.
  5. Ensure all connections are sealed properly, applying exhaust sealant if necessary, then tighten to the manufacturer’s torque 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 engine control module (ECM).
  3. Start the engine and let it run for a few minutes to ensure everything is functioning properly.