Is camshaft failure a common fault on the ASZ 1.9tdi engine? On idle the car makes a clicking/slight knocking noise can't figure out if it's top end or bottom end and progress' s as engine is revved only just noticed noise today and car has been stood all weekend

Not as far as I'm aware, although its important to use the correct oil or I believe wear can occur

It can happen but more prevalent on pd150 Golf.

If it's stone cold, the problem could be more or less anything. Take it for a drive (gently) and see if it does it once warmed a tad.

 

As for cams, easy to knacker a PD cam. Just don't change the oil regularly/ever. This shouldn't be an issue on a top-of-the-range motor - you'd hope.... But plenty of 1.9PDs in lesser models too.