My CEL won't go off, and when I try to pull codes, I get none :(

The CEL is on consistantly and even after disconnecting the battery I still have the light on.

Any ideas?

the car starts, and drives just fine. A slight unsteady of the idle when cold, but after that it runs like a well tunes sewing machine.

I've replaced in the past few months the following parts:

Air filter
Oil and filter
Fuel filter
Wires (the more pricey set with the lead wire for i motors)
o2 sensor
Intake boot

Not sure if this has anything to do with it, but the CEL only started after I had my clutch and slave cyl. replaced. I'm pretty sure that they dont' have anythign to do with it, but I've checked around the engine bay and nothing looks out of place. The engine did sound a bit rough after the clutch job, and that's when the CEL came on. There was also an exhaust leak, but that's been addressed since then and the light still persists.

Ive also checked the ICV and it seems to be doing it's job properly as well (no fully idle or anything). It was suggested that my ECU could be causing the problems, but it's the newer 173 version that I'm running with the stock chip (also running regular fuel which has never goven me issues before). I do have some missing electrical insulation on my wiring that runs to the o2 sensor caused from some mice during storage, the wiring was always exposed with no problems before, and my fuel economy seems fine too.

Any other ideas? Any other things I should check under the hood?

thanks in advance

88 Delphine grey 325is
Membership ID (00013)