My wife 02 A4 Avant when very cold (last night it was -4F) will beep from some unknown loaction when reversing. She tells me if you let it warm up it won't happen.

Any ideas? Is the car telling us I'm not warm enough to move yet?

 

i dont think i've ever come across any threads for that've mentioned a beep in reverse. The only thing i can think of and is highly possible for an '02 is that the rechargeable back up battery for the alarm system is on its way out. in sedans it's located somehwere under the backseat i believe and is not an easy fix. i would recommended that you try your best to isolate the location of the beep.