my BMW 5 Series G30/G31 (2017-2024) check engine light is on and won't turn off

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, torque wrench, vacuum gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Diagnose and Address Error Codes

• Connect the OBD-II scanner to the vehicle's diagnostic port.
• Retrieve and note down any error codes.
• Research the meaning of the codes to determine the specific issue (e.g., P0420 for catalytic converter efficiency).
• Address the codes based on their priority and severity.

3. Inspect and Replace Faulty Components

• If error code indicates a faulty sensor (e.g., oxygen sensor):

  • Locate the sensor based on the error code (pre-cat or post-cat).
  • Disconnect the electrical connector and remove the sensor using the socket set.
  • Install the new sensor, ensuring it is torqued to the manufacturer’s specifications, and reconnect the electrical connector.

• If error code indicates a vacuum leak:

  • Use a vacuum gauge to test for leaks in the intake system.
  • Inspect and replace any damaged vacuum hoses or gaskets.

4. Reset the Engine Control Unit (ECU)

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the error codes from the ECU.
• Start the engine and ensure the check engine light does not return.