Where is the sensor that detects low coolant level? on 2002 Mercury Sable

The "low coolant: light comes on even though the radiator and coolant reservoir are full.

Asked by for the 2002 Mercury Sable
you must buy the whole assm from ford,and it willn not be cheap
2 more answers
it should be in the resrvoir
Bottom of reservoir and looks like this;_ylt=A0PDoKsdbw9Rtm4ASG6JzbkF;_ylu=X3oDMTBlMTQ4cGxyBHNlYwNzcgRzbGsDaW1n?