4.9 Sensor location

My son recently picked up a 91 Deville with a 4.9 that he is using for a school car. There is a light that flickers on and off on the dash that says "Stop Engine Temp" it is also accompanied by a dinger that goes off. I see there is also a light for coolant temp. The engine seems fine runs good and shows no signs of over heating. Does anyone know where the sensor is that controls the "Stop Engine Temp" light?

Thanks

Its the sensor located between the EGR valve and the thermostat. Looking at the engine from in front of the car, it is just to the left of the thermostat housing.