Outside Air Temperature Probe...

[snpower]

I bought a replacement one as the OBC display reads '160' all the time. No change.

What else can I check to get this working, and does it in any way affect engine performance?

[Bear]

Check the wiring all the way back from sensor to OBC. I have found that bad conncectors at the sensor can cause problems and I have built a few of my own using male/female bullet style connectors and crimping them on the wires.

[snpower]

I've followed the line back to the firewall. Coming off this line and underneath the fuse box I found a connector, similar to the plugs that attach to the probe, that is not plugged in. I don't know if this is related to this problem, but I cannot locate where this harness plugs in.

[Bear]

Wiring diagram here:
http://shark.armchair.mb.ca/~dave/BMWe30/

[Bear]

E30 (1983 to 1992 3 Series) Wiring Diagrams

[snpower]

Awesome. Thanks.

[Bear]

No problem, glad to help, and the wiring diagrams are pretty important and I just happen to have them saved in my PC, pass them on as you see fit.