My girlfriend just bought my grandparents 2000 VW bug(diesel). It had a home in a nice warm garage and was driven almost daily like every other car, however my girlfriend has only owned it for about 4 days now and the check engine light has come on. It has been extreemly cold (into the teens) and no longer sits in a garage, i put a diesel additive to keep the fuel from jelling in it. But i am really confused because if she starts the car and lets it idle, the check engine light stays off, however if she puts it in drive or reverse the light comes on after a little bit of time.
Could this be fuel related? what other things could be causing this? Any help would be greatly appreciated.
Patrick