Check Engine Light On While Car Off
 

I did a search on my problem with no success.

Recently replaced my altenator after it died on me driving home from work. A couple of days after installation of the new unit, I noticed the check engine light was on in the car as I approached it. The car started with a little hesitation and less than 1 minute later the check engine light went out and stayed out for the duration of the trip.

Got home, turned the car off and waited a couple of minutes and sure enough the light came back on. I re-started the car and the light went out. Turned car back off and and light came back on. Have been driving like this for a few days, however the car starts and drives fine.

Had the battery replaced thinking it was an indication of a weakening battery since I did drain it when the altenator went bad on me and the car was running purely on battery for a while. Since I changed the battery today, the light still comes on when I shut off the car.

I am taking it back to the shop that installed the altenator and have them check it out, but I would like to go in there with a little knowledge as to what some of the possible issues are.

Has anyone heard of this before? If so I would greatly appreciate input regarding this matter and if no prior knowledge of this I would also appreciate your oppinions.

Thank you.

what kind of mbz is that

I forgot to give the specs on the vehicle.

I have a 1989 300E W124.

The most recent history on the vehicle is:

Altenator: Jan 08
Tune-Up: Nov 07
Engine & Transmission Replacement: Sep 07