1999 Sl500

Outside air temp display reads -35 degrees F constantly. Anyone have any ideas on troubleshooting this system or where to get temp sensor? Thanks

[Mike Miller]

The same thing happened to my wife's 525i. In addition, those clever guys at BMW decided that if your outside temperature was, in her case -45F, you obvioiusly don't need air conditioning! She knocked her sensor off on a curb on a hot summer day and drove home with no A/C as well.

The temp sensor probe is a bi-metalic resistance type. In other words, if the the sensor is disconnected, your car will show a complete open circuit and the temp will go to as cold as your gauge will read. Thus, the same in the hot direction for a dead short. I would check the connection and then as much of the wiring for a break as I could. You might want to try using a short jumper wire and short the connector at the sensor. Your temp should go to the very hot position if your wire harness is OK. Then it is just a matter of a new sensor probe.

[LeaUK]

I agree, the system is reading an open circuit so check wiring at the sensor first as this sees the most hostile environment.

Lea