Another 'whats this?' question. Loose wire in engine bay

[jimf]

Hi folks, whilst spending some time under my 325i cab project i found this loose plug. One end goes into a sensor on the block and one looks loike it goes into the injector loom. But where should this bit go??

[BMW_E30vert]

i have the same loose wire on my pre facelift car, but cant seem to find the wire in my facelift cab

[jimf]

I've had quite a few older bmw's now but on this one i can't tell which wires are stock and which have been added over the years. Would love to see if all these bits were hanging loose and looking like some cowboy has had a go when it was in the showroom.