My 320E won't fire up if the key has been left in the ignition (in the off position) for a few minutes. The engine will turn over just fine but not start. On most occasions if I take the key out and leave it out for a few minutes it will start up just fine. Whats going on here. There is nothing in the user manual to explain this? Any ideas as it is a real nuisance.

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1993 320E 140,000km