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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical issues.
• Allow the engine to cool before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• If the O2 sensors are found to be faulty during diagnostics, follow these sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an O2 sensor socket to unscrew the sensors from the exhaust system.
  4. Install new oxygen sensors by threading them into the exhaust system and tightening to manufacturer specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting torch (if applicable), welding equipment (if applicable), gasket scraper.
• If the catalytic converter is clogged or damaged:
  1. Remove the exhaust components that obstruct access to the catalytic converter (this may include exhaust pipes and heat shields).
  2. Detach the catalytic converter from the exhaust system by using a socket set to remove the bolts.
  3. Clean the mounting surfaces with a gasket scraper to ensure a proper seal.
  4. Install the new catalytic converter, ensuring it fits properly and is secured with the correct torque (usually around 25-35 ft-lbs).
  5. Reassemble any removed exhaust components.

4. Reset the Engine Control Module

• Tools Required: OBD-II scanner.
• After repairs, reset the ECM:
  1. Reconnect the negative battery terminal.
  2. Use an OBD-II scanner to clear the P0420 code and any other stored codes.