my Ford Mustang S650 (2024-Present) has a check engine light with code P0420, what's the fix?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool before starting.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Disconnect the electrical connectors of both sensors.
  3. Remove the sensors using an oxygen sensor socket.
  4. Install new oxygen sensors (ensure they are compatible with the 2024 Mustang S650).
  5. Torque the sensors to the manufacturer's specifications (typically around 30 lb-ft).
  6. Reconnect the electrical connectors securely.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  1. Remove the bolts securing the catalytic converter to the exhaust system using a socket set.
  2. Carefully detach the catalytic converter from the exhaust pipes.
  3. Inspect the internal structure of the catalytic converter for blockages or damage.
  4. If necessary, install a new catalytic converter, ensuring proper alignment with the exhaust system.
  5. Torque the bolts to the manufacturer's specifications (refer to service manual for specific torque values).

4. Clear DTC and Test

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear any stored codes.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.