found this

down the back of the expansion tank, does anyone know what it's supposed to be connected to?

PS. it's not the brake fluid reservior one that's a similar shape, that was connected

There is a connector like that on the top of the expansion tank on some models, I think it's a sensor of somesorts to tell you when the coolent is low, but quite how it works I don't know, as I've never seen a light for it to notify you!  If your expansion tank doesn't have that connector on the top, then it's probably not used on your model and you can probably dis-regard it. Looking at it, it doesn't look like it's been connected to anything for a while!

I've got various spare connectors in my engine bay, VW obviously used the same wiring loom in a lot of different models.


Mike.

Correctomondo….! It does sit in an electrical plug on the expansion tank! I snapped mine fitting a strut brace….   ops:
Karlo