A little Electrical Help Please

[mlong]

I recently acquired a 1989 35hp Mercury OB and have been working to get it back in shape. So far so good. But while searching for loose wires I came across this wire located to the side of the top spark plug. Not sure exactly how it connects to the head, and Not sure where it goes or what it does.
Any one with any insight? Much appreciated.

 

[racerone]

Overheat warning sensor I believe.----All looks correct to me.----The lower sensor is for a temperature gauge.

 

[mlong]

Thank you. I had assumed the overheat sensor and the senor for the gauge was one in the same! Thanks for clarification!