The engine management light on my Mk 3 GSi Astra comes on almost every time I drive it and when its on it rev limits at 4500rpm. If i turn the engine off for a while it then runs ok and may come on sometime after. But if I turn it off and then try straight away it doesn't run (cranks over though). It's only got 25000 miles on it and isn't due for a service? Any ideas? I've booked it on for a diagnostic test on Wednesday but was just curious as to your opinions.