OBC Readings

I have '92 325i just purchased. The OBC ambient temp shows -34F. Does this mean temp sensor is bad? Where is it located? Previous owner just upgraded A/C sytem to R134a. Would this have anything to do with it?

yes, it should be in one of the lower panels in front of the front wheels.

For a couple of weeks, mine read 191 degrees during the day, 161 degrees at night. Now it has settled down to less than 100.
Flunky