[Jemellh]

Does anyone have experience wiring a ambient sensor to the ecu? I bought a 08 528i the car had small front end damage. The front bumper needed to be replaced. Im assuming during the accident the ambient sensor was pulled off and the wiring is gone. I bought the car fixed already, but my mechanic was telling me the wiring is gone and my ac is not working. He claims he has to wire it to the ecu. Was wondering if this is a difficult task.

 

[toga94m]

You're looking for the sensor that reads outdoor air temperature, which displays on the dashboard? Looks like that one lives under the front bumper, if I've chosen the right one at bmw-planet.net
There's also a little bit of info in this writeup -

The ambient temperature sensor is not directly linked to the engine control module but to the instrument cluster. The value of the ambient temperature is sent to the engine control module via CAN bus. In the event of a fault, the instrument cluster sends a characteristic value which the DME interprets as a fault.

If a fault is entered, a substitute value is calculated for the ambient temperature from the intake-air temperature. The ambient temperature is required for many functions in the engine control module that contain temperature-dependent parameters.

From the wiring diagram, you're looking for two wires : blue/red and blue/brown that'll end up at pins 4&5 connector X16 (an 18-pin part on the back of the instrument cluster)

 

[Jemellh]

Yes that's correct the car is reading -40. thanks so much