Yes, its the blow by gases escaping by the easiest route e.g.....the borken pipe.
The blow by gases will have some oil content.
The sensor has no through passage so when connected correctly no harm will be done.
I guess the turbo seals, given some miles, may generate a samll amount of oil in the intake as well...
Possibly but not so likely on TD's as they have a much easier life than turbos on petrols
Funny you should say that - there's a 2.5TD on fleabay at the moment listed with a 'blown turbo' .. I have my doubts a about that and I'm almost tempted to take a punt on it for precisely the reason you say.
Cheers for that guys.
Pitty its another €129.00 + vat off the garage
Already after putting two new shocks in it this month aswel as all the bushings and track rod ends
The joys of motoring

Bejeezus! Did you buy it already? If not, I have a used as-far-as-I-know-good one sitting in the toolbox that you're welcome to for the price of postage and a wee bit to cover a couple of drinks? (Took it off my old 2.5TD when I was playing find-the-fault-that-turned-out-to-be-the-autobox

, it wasn't throwing any codes so I believe it to be a good sensor; they're electrically very reliable)