today i drove the car to college with no problem. I came home and after 2 hours i went out with the car it was all fine and good nothing wrong. I stopped to go down and eat parked the car and turned it off, after i finished eating i went to my car and saw a the check engine light on. I than went to autzone to read the code which was U0100 they had no idea what that it is. I then went home turned the car off and waited 20 sec and turned it back on the check engine light went away i was happy. I still want to know what it is and why did that happen can anyone plz tell me what is it and what caused it to go bad and what should i do to fix it? anything that is helpful. the car is a 2008 bmw 528i the car is clean nothing is wrong with it