I am trying to locate the ambient temperature sensor in my '03 R50 and not having any luck. I'm getting conflicting info on which side of the car it's on and I'm starting to wonder if it's there at all. I have a set of wires with nothing attached and since I've had the car, it's always read -40°. I believe that temperature is what that sensor would be reading, correct ? Can anyone shed some light on where exactly this thing should be? Thanks in advance!

 

You may have already seen some videos addressing the same -40º temp reading issue as you have with your R50...

Although I don't have an R50 (mine is an R53), by al accounts; the outside ambient temperature wiring and sensor on an 1st gen R50 looms through the left front/driver's side, aluminum (crash) bumper carrier.
On my '04 R53, the outside temperature sensor looms through the crash bumper and is retained by a plastic clip between the <bumper cover> and just in front of the radiator. It can be viewed from the top looking down between the 2wo with the hood open.
Oddly enough, the Bentley manual does not index the Outside Temperature Sensor but references (page 510-7) - "pulling out the electrical harness for outside temperature sensor through the opening in the bumper carrier".
The picture in the description seems to show the sensor just dangling there by its wire?




Given that the Bentley is regarded as "the" service manual for these cars, one would expect more clarification as to where the sensor resides and should be retained. Not just dangling there on hopes and prayers that it won't get damaged.

Probably not not much help from me....
Just thought I'd share what info I had.

 

On my ‘06 it clips into the bumper cover.

 

Yep - my mistake...
What @deepgrey said = clips to the bumper cover.

 

A reading of -40 degrees is usually an open in the circuit. One time while getting to service mode, I forgot to pull the ambient temperature sensor wire through the bumper and when I pulled the bumper off, I broke the wire. I would make sure the sensor is there and fully connected.

 

Shown below on my 06 MCS is the cable with sensor at end routed forward of the bumper carrier with the bumper cover removed and sensor unclipped (replaced lower chin spoiler/air dam which had been damaged by lowered suspension on our local streets)...