172 Will not start - Need help identifying where a plug goes.

[RickyJanez]

Hi all

My 172 broke down on the way home from work last week after being faultless in the year I've had it. The engine cut out whilst at low speed and will now won't restart.
It tries to turn over, starter motor is working and there is compression. The electrical fault light has come on (Orange light with squiggly line) I've been having a poke
around under the bonnet and unplugged/replugged in connectors but have a mystery connector and I can't figure out where it goes:

The car has been "messed with" before I had it but put back to standard(ish) so I don't know if this plug has worked it's way loose or is something non-essential
that a previous owner has left unplugged. Should be obvious from the pictures but it comes out near the bottom of the airbox. Anyone have an idea where it should go??

 

[MicKPM]

I'd have said power steering pressure switch from the First pic but after seeing the second I'd say it's more likely to the the acoustic valve behind the passenger head lamp.

 

[Matt@codered]

Possibly a tdc sensor and loom?
Check to see if it's had the later one fitted, should be blue in colour for the new one, black for the original one, located on top of the gearbox.