tempertuture sensor

[SilvioD]

Hello I am a new member to this forum and this is my first post. I have a 1981 520i. Can someone tell me please which of the 3 tempretures switches is the one that controls the cold start sensor.
Thanks

[Shawn D.]

Hi Silvio,

Welcome! Please read and heed the Tech FAQ and Forum FAQ sections.

I am moving this to Tech Talk, as Comments is not the place for technical questions.

[Mike W.]

While I'm not familiar with 520i's per say, I've had numerous K jet, L jet and motronic BMWs from the 70s and 80s. The thermo time switch, which is a switch, not a sensor, controls the cold start valve. It's the largest of the sensors/switches at the front of the head and the plastic part is brown, along with the connector that goes on it. Also, very important, it only allows cold start operation for a certain length of time (6 seconds?) before it shuts it off. And it only operates during cranking. It's a cold start device, not a warm up or cold running device.