Hi, there's a blank on no 3 cylinder, right by the turbo. large Allen key to remove, then you'll need the temp sender, and an adaptor to plug it into.
It's a bit of a pain to get to, needs the intercooler out. Have a look see if it's there already, possibly a wiring fault.

 

The other option is to use the oil pressure sender point under the alternator, it's easier to get to than the cylinder 3 blank, and get hold of a t-piece so you can keep the low pressure light sender in place.

LMA do it as a complete kit with the braided extension hose. I just need to sort out the fixing point, but it has worked fine for the last 18 months.

 

Yeah, i read your post as temp not pressure for some reason, ignore me! As above!