This light seems to come back (after having been reset) whenever one of the rear wheel slips even a little under power. I noticed it come on when under slight acceleration turning right from a stop.
This time my mechanic hooked up to the computer and indeed tracked the error coming from the rear differential. He did a bunch of other stuff to the car that was unrelated but that's as far as we got with the red check engine light. Of course, within a few days, it's back.
Having spent way too much on engine and much more, I'm reluctant to ignore this light. At the same time, I'm getting sick of putting more $$ into her.
Has anyone seen this before?