Can someone tell me what this thingy is and where it should go?

Hi Guys,

I have this mystery sensor (?) that has never been connected to anything since I've had the car. It's been tucked up out of the way so I forgot about it, but I thought I should probably find out what it is and where it goes.

It comes out of the loom behind the drivers side head light, where all the lighting plugs come out.

 

Model and year as well as engine would be a help…
I don't recognize the plug, but if yours is a Diesel, or a gasser see where it goes, as that was the general area where my block heater plug went on my 81 Rabbit Diesel LS…. yep I'm a Yank. Well actually a Reb, as i live in the southern U.S. …..
 

Good point.

It's a 1982 GTI 1800 DX (so petrol)

My first guess was that it's the outdoor temperature sensor for the MFA? 

Lives on/in/behind front bumper.

its the outside air temperature sensor for the MFA clocks.  there should be a bracket attached to the bumper for it to clip into, but 99.99999999999999999999999999999999999999% of the time its snapped off, so just cable tie it somewhere securely

Excellent! Thanks Jonny, that was my guess.

Cheers.