Hi looking for some help here :-D this is none skoda related but been told that some skodas have the same engine as mine the 1.9tdi pd130 so story starts my turbo broke on my seat Ibiza 03plate and I sourced a second hand 1 replaced it now feels like powers lost from the boost at low revs so got my laptop out I have the free version of VCDS and it came up with 16485 17964 fault codes took the plug off the maff sensor to see if it was that and it made it worse so put that back on don't no where else to look any advice is much appreciated

17964 is boost pressure negative deviation. So I would think either the second hand turbo is faulty or something hasn't been connected up correctly. Couple that with the air mass fault it sounds very likely a pipe is off somewhere.