Ok guys, still having the same problem. The check engine light comes on and its that same old code, Unit Control Supply. I reset the light again, does anyone have any idea what this could be? Other than this code keep coming up, the car runs great. This is becoming very frustrating. I do not want to go to the dealer. I do have a BMW mechanic and of course he tells me to take it in so he can do a complete dianostic check. You know what that means, minimum $140.00. If anyone has any idea, please let me know. Thanks!