how to fix the engine light and code P0420 in Ford Explorer Sixth Generation (2020-present)?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery for safety.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use an O2 sensor socket to carefully remove the sensors.
  3. Inspect the threads and connectors for wear or damage.
  4. Install new oxygen sensors, ensuring to torque them to the manufacturer's specifications (usually around 30 lb-ft).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter for physical damage or excessive carbon build-up.
  2. If replacement is necessary, unbolt the catalytic converter from the exhaust system using a socket set.
  3. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  4. Torque all bolts to the manufacturer's specifications (typically around 25 lb-ft for exhaust bolts).
  5. Reconnect any heat shields or brackets removed during the process.

4. Reset the ECM

• Sub-steps:
  1. Reconnect the vehicle battery.
  2. Use the OBD-II scanner to clear the P0420 code from the engine control module (ECM).
  3. Perform a test drive to ensure the check engine light does not reappear.