1. Ensure that the gas cap is properly tightened and closed.
2. Start the engine and let it run for a few minutes.
3. Turn off the engine and wait for a few minutes.
4. Start the engine again and check if the service engine light is still on. If it is, repeat steps 2 and 3.
If the service engine light persists after following these steps, you may need to take your car to a BMW dealership or a qualified repair shop to have it diagnosed and repaired.