Boost pressure solenoid valve

Anyone know the location of this? And can point me in rite direction to purchase one?
Thanks

What car and production year ?

Hi, it's a 2004 A6 3.0 tdi thanks

Sorry, not familiar to

Do you mean the N75 valve? If not, what is the valve code? Tell me also engine code and auto or manual and I will provide location.

Thanks. It's turned out its the actuator on the turbo, been told whole turbo needs replacing. It's a 200r Audi A6 3.0 tdi.