Recently got a service from ford dealership, £209.

I was then quoted £196
for my two failed front wheel TPMS sensors

£446 for rear discs and pads
(both rear wheels)

£625 for ALL 4 door weather seals to be reattached
(about 4 inches hanging off)

Then they've tried to charge me £35 for
brake fluid aswell because they said the fluid was contaminated.

Long story short l've just done weather seals myself, I've just done the brakes myself,
And the TPMS sensors l'll have done for £100.

Due to the high prices of the
weather seals and a rattling sound when driving; I got a bit paranoid and its
a good job I did. I popped the bonnet and was welcomed by a telescopic
magnet fishing tool wedged between my turbo and engine block. I pulled it
out and thought I'd ring them back tomorrow and let them know that I will
bring their tool back in for the tech.

But now my brother has told me that
if he's left that tool there, (most likely using it to find a socket or bolt that's
dropped somewhere) then he may have forgotten to do something else, and
also to check if any damage has been done from the tools presence. So l've
popped the bonnet again just to check that air filter had been changed and
that nothing was loose around it, but right next to the air filter I've noticed
something unplugged, and I can't seem to find where it goes, so for one; can
somebody give me some advice on what to do now as l'm not sure if the tool
has done any damage but I know for certain it's been rattling around for the
past 3 days as the noise has now stopped since l've removed it. Also does
anybody know where this goes? You can see in the picture the area located
Its a two pin plug and was hoping somebody else could give me a bit of
closure, maybe it's a ghost plug that isn't needed for my model of engine?
Should I call them or visit them about this? Thanks in advance, I'm a train
technician so I know the basics of how engines work, just I don't have the
knowledge of a car engine as much as some of the mechanics on here
Plug is on the right hand side of the photo, left of the airbox

Car is a 2014 Mk3 Ford Focus EcoBoost 1.0 3cyl. (l welcome ecoboom
jokes)
 

That's the cylinder head temperature sensor.  If you haven't noticed any problems with it unplugged, it's probably not used on your car.

The original cylinder head on my (2012 reg. Focus) car did not have a temperature sensor (position blanked). The replacement head I fitted (circa 2015) came with a sensor. There was nowhere to plug it in and, because I had the head on the bench, I just decided to remove it. Hasn't created any issues. I would just tie wrap the cable/plug of yours against the adjacent head earth strap to keep it from moving around.

 

Factoids for interest: The sensor is screwed into the head but the sensing tip is not actually in a coolant waterway. It just sits in a hollow cavity machined into the head casting. Provision for the sensor has been present on the casting from the earliest 1.0 engines but on many engines it's just left blank (no hole, no thread, no sensor).