Hi, I have a 97 M3 with no mods. One day the car was driving great -- except for a rattle underneath which turns out to be a problem with the Catalytic Converter -- then I let it sit for about a week and when I tried to start it--nada, battery dead. So I got a jump and took it to the dealer. While I was driving there, the check engine light came on.
The dealer said: 1.) my problem was the battery was bad and 2.) the check engine light was cause I didn't have the oil cap on tight (had recently put in a quart).
Fine. Got new battery. Dealer tightened oil cap.
Drove for a bit and check engine light came on again. Two days later: battery dead. Damn dealer. Took it to an independent mechanic. After investigating it in his garage for a week, he called and said the DME was probably bad. The idle control was staying on when the car was off, as was the DME itself, draining the battery. He said I had Oxygen Sensor problems too, due to the Cat Problem...
So now I am disconnecting the battery while not driving it contemplating either getting a new DME or selling it.
Anyone ever have a DME problem like this. Is replacing the DME the only answer? Is the O2 and the DME troubles related in any way?