E30 Temp Sensor Problem

Hello guys, i have a problem ive been tryin to figure out for a while. i have a 82 e30 prod date 84 engine M25 in there everything is working fine but when i turn the key on without even starting the car, the temp gauge goes directly to hot. any ideas why?? thanks in advance

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW E30 Coolant Temp Sensor Replacement

[Wayne 962]

I believe that when these sensors of fail they default two hot. In other words when the center becomes disconnected the gates sees that it's disconnected and then defaults to full hot. Because of the false the full hot it tells you that the sensor is not working or the wire is disconnected. So I would check in the engine compartment and make sure that the wire to the sensor is properly connected. If it is connected then the problem is a faulty sensor most likely.

- Wayne