I have a 3 prong female plug hanging lose next to my oil filter..What is it too?

What is your question?

It is about 10 inches long has a yellow head it;s a female 3 prong and it is a wire. It is wrapped in some kind of tape for heat protection. It seems to be connected to a small bolt in to the frame to the right of the oil filter about 5 inches back.It wasn't hanging down the last time I checked. Can't find what is is suppose to be plugged into