my girlfriends 1999 beetle's check engine light keeps coming on. we brought it to a mechanic twice. the first time they said it was probably the back o2 sensor, so we replaced it. that wasn't the problem. the second time they put some fuel injector cleaner in it and we also had given it an oil change. that also did not work. the car seems to run like normal, the light just keeps coming on. if anyone knows what it might be please let me know. thanks

 

go to autozone and get the codes read for free. then post them up here

 

There is so many things it could be... I would take it somewhere else other than your mechanic just to get another read on it. Ive had an issue with mechanic cuz his machine overlooked small repairs. So in your case it might be the same as mine. Again its hard to tell what it is unless you post some codes up here.

 

like i said. just go to autozone it's free.

 

run a vag com on it and post up the code.

 

or that ^

 

i dont know the code, but the mechanic's machine said it was running lean in bank 1. whatever that means. forgot to post that lol sorry. if nobody knows what that means I'll take it to autozone to see if i can get a code.

 

is it running hot? check the t stat, CTS, MAF, IAC

 

check for any vacuum leaks if no vacuum leaks i will lean more to a bad mass air flow sensor

 

if he had a vacuum leak significant enough to throw a code he would feel it at idle, so unless he is not telling the whole thing then I kinda dont think its a vacuum leak.