I recently replaced my thermostat and coolant temperature sensor on my 2002 ZX2. The temp gauge was fine after replacing the thermostat (2 sensors I bought from 2 different auto parts stores did not fit so I had to buy it from the dealer a few days later. Now after replacing the sensor, the temp gauge stays in the center position even when the car is off and cold. I even tried disconnecting the battery but that does not make it move. A Ford tech told me if it's unplugged, the gauge should pin one way or the other. It also goes slightly past center when the car is being driven, but seems to center again when the heat is on. Is the sensor bad? Wrong part? ( the box says sensor but my receipt says sender. But I know the sender screws into the engine. The sensor is held in with a clip) Any other ideas?