Uh Oh

[kevintb7]

So im driving along normally and notice a check engine light.....
i also noticed the engine temp was almost in the blue for cold...

i pulled over asap and shut off the car turned off my subs etc and then started her back up... everything sounded fine from inside and after driving for about a minute the engine temp was back to normal but the check engine light was still on..... i pulled over again and opened the hood to listen, there was a very faint noise coming from possibly the alternator ish area...

this scared me because i finnally turned my system up for summer and noticed my headlights dim with the bass....so i figured thats not good for the alternator and i was going to get a capictor pretty soon....

anywho i switched my radar dector to read the voltage and it read 13.0 (for some reason it only reads like 13.5 max...) so i figured thats ok because the subs were on earlier and it remained the same 13.0 the whole way home

Any ideas? my mechanic claimed he couldnt scan bimmers im not sure why, if someone could fill me in that would be good. We have a really nice scanner at school and i know we have the plug to fit it and its OBD which our scanner works with..is there some special thing with bmws?