BMW Repair: Temp gauge shows cold all the time, long periods of time, temp sensor

Question
I have a 92 325i and recently (within the last month) the temp gauge rises as the car warms up but stops just above the cold (blue box) on the gauge even after teh car has been driven for long periods of time.  When it was operating properly, the temp needle would advance to the mid way point on the gauage.  Changing the heater temps and fan speed has no impact.  I suspect the thermostat is malfunctioning/stuck - am I correct?

Thanks
Mike

Answer
Mike, not a bad idea, but try the temp sender unit in the therostat housing first. Find the temp sensor that is responsible for the gauge (there are like three temp sensors right next to each other) Pull the connectot and observe the gauge with the connector open and with terminals shorted together to make sure the gauge works. You can do this without the engine running.  
-Evan