First of all I'd just like to say that I am new to the Forum and would also like to say Hi to all the forum members

Now for my issue

early this year I brought my A3 but shortly after I was driving up the motorway at 50 or so MPH in 6th gear but when I put me foot on the down to accelerate the car went in to limp mode

after pulling off at the next services and turning the ignition off and on again the car then seemed to be ok

the problem that I am now having is the that there seems to be a constant whistle from the turbo and around 2000-2300rpm I get a noise like you would get from a blowing exhaust

If I am in a high gear at low speed and accelerate the engine goes in to limp mode

the only code on the ECU is 16618 Boost Pressure Regulation: Limit Exceeded ( Over boost Condition )


Things that I have done up to now

I have put a vacuum gauge on to the actuator feed pipe and get the following

at idle 800rpm the vacuum is -20psi
if I let the vacuum go below -2psi I get Overboost and limp mode

i have also put a vacuum pump on to the actuator and at -20psi the actuator is fully open

could any one please help with my issue

thank you