Would be worth a try. I checked on the Gentex sensor and got the feeling they don't want to sell the connector with the sensor. Do you think they mounted one of those sensors even on the TDI, or just the GLX B4s? I could check my parts car when I get home. If someone has one, if they could measure the resistance and outside temp, I could just order a thermistor from Digikey and make my own.
Good question, I had run across a 95 B4 GLS (4 cyl) car that had the sensor in the front bumper opening, but what I don't remember is whether the car had MFA or not. For some reason I think it did because someone asked me to get the cluster for them and then realized it was an AT car and didn't want it.
I just don't remember the specifics, the only reason I would say maybe is because they wired up all B4 cars for fogs even though they didn't install the lamps on GLS or TDI versions. I do know that you could get the MFA feature on the GLS cars so it wasn't exactly exclusive to the GLX six cylinder cars.
I don't know, for some reason I seem to recall finding a temp sensor on a car that wasn't wired for MFA. But which car that was I can't say at this point, it was several years ago.
I added the wiring and sensor on my B3V when I was working on the wiring but I don't remember where I installed the temp sensor wires in the main harness. I'm sure if I go back and look at my wiring notes I'll find it.
Steve