It could mean anything. The ECU did find a fault in your engine somewhere, however after I believe 3 complete cycles of the engine, if it deos not see the fault again it will shut the light off. The error code will still be in your ECU but you will need a code reader to know what it is. If you plan on keeping your BMW for a while you should buy one, since it costs the same amount as bringing it to the shop for a diagnostic anyway.
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