I was having a dig around the engine bay today while checking over a few bits before I undertake my first T25 service, and I noticed this little kiddy on the left handside of the engine bay.

I believe it is the Idle Stabilisation sensor/valve/unit (one of the above) but noticed at some point in the past it has been disconnected.
I understand it may be common practice to disconnect and link the wires together (as shown at the bottom of the picture) when doing the engine timing....but I would assume once the timing is done, you would connect them back up.
I have not tried reconnecting yet, but with my limited knowledge Im not sure how it will affect things if it has been left disconnected for a reason. Maybe it stopped working, maybe it was forgotten about.
What are your thoughts on this? Has anyone had much dealing with this issue?? I assume it is fairly important otherwise it would not be there in the first place.
Ta in advance.
