When you have the car scanned and the light is out did your friend check the history codes? There are two sets of codes to read, current & history. Current for when the light is on now when tested, History when the light came on, then when out. After you get the code you can go to sites like http://www.autoreairs.about.com/ or http://www.obd2-codes.com/trouble_codes? pretty much anything with the obd2 in it. I hope this helps, Good Luck. :^)