It comes on but it has the correct amount of coolant. I have checked it both when cold and after running awhile. Temperature gauge indicates temperature is normal. If I stop and turn off ignition the light goes off.
I am assuming it is a sensor that is going bad. Any suggestions?

I had that problem with my 97 Sunfire and found it was one of those environment warnings. It turned out to be my gas cap wasn't fastened down tight enough. There is no telling what light is going to show when this happens. Go figure !

It's a common problem with the Taurus. It happened to my 2000 and I disconnected the 2-P connector on the underside of the degaser (coolant reservoir). There's really no way to eliminate the problem, without replacing the item or disconnecting the wire to the sensor.