Audi Repair: Coolant temp gauge, coolant temperature sensor, coolant temp

Question
QUESTION: My coolant temp gauge is giving me some problems.  The gauge would usually read in the middle and now it reads only one slash up from the cold side.  I have replaced the coolant temp senor located on the back of the motor close to the fire wall.  But the gauge still reads on the cold side.  Any help would be great.
Thanks
Jon

ANSWER: Was that the coolant temperature sensor or the temperature switch?  Did the part you replaced have two or three wires going to it?  Let me know,  Jan

---------- FOLLOW-UP ----------

QUESTION: It was the 2 pin thermal switch (Green in color) and it had 2 wires going to it.  It is located in the cooling pipe running between cylinder heads.
Thanks - Jon

Answer
Hi Jon,

I think this is the temperature switch.  Typically the temperature sensor is located near the thermostat, what model and year car do you have?  If you disconnect one of the wires, does the warning light come on, or does the gauge go to min or max?  Let me know,

Jan