charge pressure control?

[2003 a4 sport tdi 130]

bit worried.... got a vag check today after getting fed up of an annoying whirring noise coming from engine after 40 miles ph...had assumed it was cause i changed my tyres....

fault code 17964 charge pressure control - negative deviation p1556 35 00
SHOULD I BE WORRIED???

HELP PLEASE!!!!

 

[2003 a4 sport tdi 130]

please help me out here guys.... someone must know what charge pressure is????

steve

 

[vw754]

nothing worry about,check all you hoses for any splits. Also check your n75 valve.Boost Pressure too Low
Hoses/Pipes incorrect connected, disconnected or leaking
Charger Pressure Control defective

• VNT (variable nozzle turbo): nozzles stuck

Solenoid Valve for Boost Pressure Control (N75) defective