I have a Prosport oil temp. gauge and when I 1st installed it, it worked just fine. After not too long it stopped reading temp. Still lights up and when I start the car it still does the full sweep, but never reads temp. no matter how long I drive. I am thinking the sensor went bad but I am not sure. What could be wrong here?

 

check the wires between the gauge and the sending unit...
maybe the sending unit is bad?

 

Check that the wires are not damaged and they haven't gotten too hot. If not that then just replace the sensor.

 

if it turns out to be the sensor Prosport sells just the sensor for all their gauges. Had to replace the map sensor for the boost gauge after an over-zealous engine cleaning shorted a bunch of stuff.