There should be two different sensors, one for the engine computer and another for the guage. You can check the resistance on both of them for accuracy. One should be located on the intake manifold near the thermostat housing. Another should be at the rear of the block or the connection to the heater core and the intake manifold. Use a glass of water and a multimeter. Check the resistance with the water at 90 F, 165 F, 190 F, 210 F. Let me know what kind of readings you recieve. Please jot them down and I will compare.