I have a E30 M3 and something weird happened today.
When I was heading home I heard a beep like the one of the speed limit on the computer. But it wasn't on, then I heard a few moments after, I checked the computer and saw that the ambient temperature was crazy. Every time it beeped it came to 0, even negatives, and then began climbing to the actual temp.......
It did this several times......

I have no idea what this could be....any ideas?????

Sounds like your temp sensor (mounted either on the (behind)front bumper or in the brake cooling ducts is either screwed or the wires / connector have come loose. Try re-connecting it to see if this solves the problem if not you may need to get a new sensor, I don't think that they are too much to buy:dunno

Hope this helps.:D

Isnt the temp sensor the little thing right next to the temo dial on the dash?

need more help....BUMP

Des is right --> this is a simple temp sensor problem,,, if the sensor goes bad, or if the sensor connector gets disconnected, the computer will think it is extremely cold as the resistance will go to infinite. you need to inspect the EXTERIOR temperature sensor (the temp sensor next to the a/c controls monitors interior temperature). there are at least two exterior air temp sensors,,, in some cases, there are three:

1) air intake for HVAC
2) exterior air temp
3) air intake for engine