My wife came home after work and pulled up in the driveway. She came in and looked back and saw red fluid dripping down. I first thought transmission but i popped the hood and it was the antifreeze coming out of this port. I checked it closely. It was on the passenger side of the radiator. There was a 3"x3" square sensor that came off of this port. Where the sensor plugs into the port it has some orings and a metal spring clip to hold it onto the radiator. Nothing was damaged. I reinstalled the sensor making sure the clips were secure and added a gallon of antifreeze. Was this thing a coolant temp. sensor? and wonder how this thing came loose? So far it runs fine with the normal temps. Just seems weird:eek:

It is a coolant level sensor, these are bad about falling out, usually one of the plastic ears that hold them onto the radiator side tank breaks off.

http://files.automotiveforums.com/uploads/820097MODULE.jpg

yeap thats it.