Trident T4 Temperature Gauge Tempremental

Good evening folks, since owning the T4 for just over a year now on start up the gauge comes up to temperature nicely, it would occassionally drop off to zero asthough it had been dis connected, then some time later would come back up to temperature as normal. More and more now the gauge comes up to temperature as normal, drops off and stays off...!!! The engine is not overheating and runs sweat as a nut, its just annoying that the gauge is so temperamental. I thought it could be a loose connection to the temperature sensor or maybe the actual senson has been slowly giving up the ghost. Has anyone else experienced the same issue or able to shine any light on what it could be.....Oh and where the actual sensor is located on the 1.9 D. Any help would be greatly appreciated.