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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative terminal of the battery.
• Allow the exhaust system to cool down before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• If the pre- and post-catalytic converter oxygen sensors are faulty, replace them:
  1. Locate the pre-catalytic converter O2 sensor and unplug the electrical connector.
  2. Use the O2 sensor socket to remove the sensor from the exhaust manifold.
  3. Install the new O2 sensor, tightening it to the manufacturer’s torque specifications (usually around 30 lb-ft).
  4. Reconnect the electrical connector.
  5. Repeat the process for the post-catalytic converter O2 sensor.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, gasket scraper, exhaust sealant
• If the catalytic converter is confirmed to be defective:
  1. Remove the heat shield if applicable (use a socket set).
  2. Disconnect the exhaust pipes from the catalytic converter by loosening the clamps and bolts.
  3. Remove the catalytic converter from its mounting brackets.
  4. Clean the exhaust manifold and pipe surfaces with a gasket scraper to ensure a good seal.
  5. Install the new catalytic converter, ensuring it is securely mounted and aligned properly.
  6. Reconnect the exhaust pipes and tighten all clamps and bolts to manufacturer specifications.