What is this sensor for?
it goes into the snorkel and the oil vapour from the cam cover breather goes through it.
it doesn't seem to change anything if i unplug the wires from it...
Are you talking about the object which is at the end of the breather hose ? Isn't it a heater to keep the vapors from freezing up?
Yup...that be what it is. I have never seen a wiring diagram that shows how/when it gets turned on, and I have seen lots of engines where it's not even connected.