Found a loose wire, any guesses? (have pics)

[hotrock3]

So as I was working on replacing my downstream o2 sensor I noticed this little guy just hangin there.

The wire hangs down around the oil filter then goes to a connector just above the oil filter that is secured somehow then it joins the rest of the wiring.





I have looked through el.pdf from index of /FSM/Altima/2001/ but I can't seem to figure out what this is exactly.

Only code a (aside from the o2 sensor code) was the knock sensor but that one doesn't pop up every time I pull codes.

Any ideas where that loose end is supposed to go?

Thanks in advanced
Andrew

[Heavy]

idk if im correct or not but dont KAs have a oil level sensor thats right above the oil filer thats branched off from the filter neck?