Hi, I’ve just recently put a new turbo on my car (a4 b7 1.9tdi) after the old one broke and it was running mint for a few weeks after doing so, however recently it’s got no boost at all almost as if it’s in limp mode. Ive got no warning lights on the dash and the only code I’ve had is p0299 low boost. I’ve checked the turbo and waste gate and they’re fine, the egr is clean, all the vacuum lines are connected with no leaks or blockages, there’s no boost leaks, the maf sensor is fine and I’ll be putting a new boost pressure sensor on tomorrow but I’m pretty sure it’s not that as I’ve tried one off a different car to still no joy. Was wondering if anyone had any other ideas of possible causes because it’s becoming a real head scratcher, thanks.

A bit of a random one, are all the jubilee clips holding all the pipes on around the turbo etc tight? 

I ask as under pressure air could be escaping from I'll fitted pipes that wouldnt be visible when idling if that makes sense