Outside Temperature Sensor [Archive] - Audi Forums

: Outside Temperature Sensor

04-23-2011, 07:17 AM
I recently bought a 98 A4 Quattro with the 2.8L. I am having a problem with the outside temperature sensor. When I first turn in on in the morning, it will display the correct temp and slowly drop down to -49. I normally wouldn't care, but that unit seems to also affect the interior temperature. I replaced the sensor itself thinking it was faulty, but have the same results. I tried to trace the wiring down the the A/C Control Module, but the junction box behind the driver kickplate is a rat nest of connections and hard to follow the lines. Any ideas on where the junction is, or how to pull the a/c module out? I could just make a jumper from the sensor the module directly to eliminate the wiring in between if I could pull the module out.
Not sure if this is related or not, but it sure takes a LONG time for the heater to warm up. It used to warm up quick, but has slowly died off. Any ideas?

04-25-2011, 07:37 PM
I had the same issue with the outside temp. Replaced the sensor behind the front grill and it did not fix the problem. Then I replaced the second sensor which is located inside the fresh air duct accessed under the cabin air filter. It was a pita to get to it and have it repalced, but it fixed the outside temp erratic reading. I am assuming that you have the climate control.

04-25-2011, 07:46 PM
Yes, I do have the auto climate control. Is it the sensor that is under the filter in the engine compartment? I found another sensor that is actually behind the a/c module that goes inside an air duct of some sort. It almost looked like it is the air intake, but didn't want to start screwing with it until I could look it up. I will see if I can find the one under the inlet filter and see how much it is to replace. Thanks for the advice!