Outside Air Temperature Sensor - BMW Forum

kohlers · 08-26-2009, 07:14 PM

The OAT sensor on my 323i is missing. Worse, there are no wires to connect it to. I can get sensor wires and connectors
(have the part-numbers), but I cannot find where to connect.
Any help?

Dirty_Tool · 08-27-2009, 12:03 AM

remove the plastic panel and look up in there. the wires probably got ripped out but there still should be some of the wiring harness left to tap in to.

kohlers · 08-27-2009, 12:14 AM

The plastic panels (the fender liners) are gone on both sides and no sign of any wires to be seen anywhere.

darkhorse737 · 08-27-2009, 12:16 PM

Quote:

Originally Posted by kohlers

The plastic panels (the fender liners) are gone on both sides and no sign of any wires to be seen anywhere.

Blue/Brown & Blue/Red wires on a connector...

**it will most likely run from a point in the harness .... front underside of car, either to the bumper or grill area.

kohlers · 08-27-2009, 12:45 PM

There are no wires whatsoever no connector!! The display shows Temp is -40F. A mechanic told me this goes into the computer and that may affect the engine (timing,fuel-mixture) although it runs just fine.
P.S. We have +100F here in Tucson.

darkhorse737 · 08-27-2009, 12:57 PM

Quote:

Originally Posted by kohlers

There are no wires whatsoever no connector!! The display shows Temp is -40F. A mechanic told me this goes into the computer and that may affect the engine (timing,fuel-mixture) although it runs just fine.
P.S. We have +100F here in Tucson.

I don't think so. If u study the electrical circuits, the OAT circuit begins and ends in the instument cluster. Therefore, no bearing on the engine performance.

The DME/ECU brain has it's own temperature sensor that gets it's signals from the engine, along with air temp measurements from the Mass Airflow meter

... definitely not from the OAT

beefrank · 08-27-2009, 01:11 PM

Does anyone know where I can get the replacement sensor panels for the driver side? With the lower clearance, I cracked the panel a couple of winters ago and it finally broke while I entered the garage. The sensor is still good and I duct taped it into the bumper for now. Thanks for your help

kohlers · 08-27-2009, 01:16 PM

Thanks a lot! You seem to know everything. I have the Chilton manual and try to find the OAT circuit. I can live without the OAT, although nice to have.

darkhorse737 · 08-27-2009, 01:42 PM

Quote:

Originally Posted by kohlers

Thanks a lot! You seem to know everything. I have the Chilton manual and try to find the OAT circuit. I can live without the OAT, although nice to have.

kohlers · 08-27-2009, 07:17 PM

Thanks. I finally found my wires. Look blue to me. They were tied up with the wire for the horn and hidden way up.

BEEFRANK. I think you talk about the splash-guard or also called Fender liner sitting behind the front bumper. BMW part # is 51718193811 for the left and xxxxxx12 for the right. The OAT is mounted on the left.
At BMW Parts, Porsche Parts, Audi VW Mini Volvo Saab Mercedes Auto Parts - RM European Auto Parts they are about $45 each.

Dirty_Tool · 08-29-2009, 08:38 PM

Quote:

Originally Posted by darkhorse737

I don't think so. If u study the electrical circuits, the OAT circuit begins and ends in the instument cluster. Therefore, no bearing on the engine performance.

The DME/ECU brain has it's own temperature sensor that gets it's signals from the engine, along with air temp measurements from the Mass Airflow meter

... definitely not from the OAT

the instrument cluster communicates with the engine module over the Can bus and I have seen the exterior temp sensor when it reads -40 degrees cause a service engine soon lamp to come on and a fault code stored in the DME. It depends on the year and model and DME variant though.