Not a clue what it means other than the ECM has noted that a sensor was outside the parameters. Even with the C4 Vettes after 85, IIRC, you can plug it into a scanner and see not only code but data stream. I know my 91 can do it.
So, what you are saying is essentially "Something is wrong". What, why, when, etc, etc, is hard to say. It might trigger a code to say something is FUBAR or that it noted something was not right when a certain set of conditions is met. Without more knowledge, it is going to be very hard to say. We can throw money and parts at it if you have more money than brains but I wouldn't think you would.
Why don't you start with the first step. Go to Autozone and have them scan it for you?
http://www.e38.org/e32/bmw%20code%20defaut.pdf