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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Sub-steps:
  • Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  • Use an O2 sensor socket to remove both sensors.
  • Inspect the threads and connectors for damage.
  • Install new oxygen sensors, ensuring they are properly torqued (typically 30 lb-ft).
  • Reconnect the sensors' electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  • Identify the mounting points of the catalytic converter and any exhaust hangers.
  • Remove the exhaust pipes connected to the catalytic converter using a socket set.
  • Unbolt the catalytic converter from the exhaust manifold and exhaust pipe.
  • Install the new catalytic converter, ensuring proper alignment and connection.
  • Torque bolts to manufacturer specifications (generally around 20 lb-ft).
  • Reattach exhaust pipes and hangers securely.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  • Reconnect the battery terminals.
  • Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.

5. Final Inspection

• Sub-steps:
  • Start the engine and let it idle.
  • Inspect for any exhaust leaks around the new components.
  • Check for any new error codes with the OBD-II scanner.