Many thanks, for your in-depth response.Yes, my 91 745 is a non-turbo Bosch system. I will try the port 6 to see if there's more feedback there. The only other code that I could get at port 2 was a 132 which would have come up when the old alternator belt failed. I neglected to mention in my original question that the vehicle appears to be running just fine and is being used for about town driving only. I may get it out on the highway this afternoon to see if that brings about any noticeable change. I haven't been able to gauge any change in fuel consumption but there's info in the FAQ that suggests that's probably happening.

I'll try that port 6 and let you know what I find.

Thanks, again.