I wondered about the left bank thing myself. Maybe it is only left bank on cars that have a vee configuration.

Yes they check that the MIL lights up in the key on, engine off position, so pulling the bulb will just get you a fail.

I have read about the wiring harness: supposedly this one has already been changed out.

Arthur Dalton gave me a few ideas through PM, I will give his suggestions a look and reply afterwards if the problem goes away or not.