how to fix P0420 code on my Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the exhaust system to cool down before working on it.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) oxygen sensor and the downstream (post-catalytic) oxygen sensor.
  2. Unplug the electrical connectors from both sensors.
  3. Use an oxygen sensor socket to remove the sensors from the exhaust manifold and catalytic converter, respectively.
  4. Install new oxygen sensors, ensuring they are tightened to the manufacturer's specifications (usually around 30-40 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Check the catalytic converter for any visible damage or excessive carbon buildup.
  2. If replacement is necessary, loosen the bolts securing the catalytic converter to the exhaust system using a socket set.
  3. Carefully remove the old catalytic converter from the vehicle.
  4. Install the new catalytic converter, ensuring proper alignment and sealing.
  5. Torque the bolts to the manufacturer’s specifications (typically around 25-30 lb-ft).

4. Reset the Engine Control Module (ECM)

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Start the vehicle and allow it to idle for a few minutes.
  3. Use the OBD-II scanner to clear the P0420 code from the ECM.