A4 TDI 1.9 turbo not boosting sometimes


Registered User

Girlfriend got a B6 A4 TDI 130bhp model and the turbo seems to be working occasionally.

With the window down you can still here it when changing gear but there's no power, although there is a slight pull down low initially.

I'm thinking a vacuum leak somewhere as there's no smoke, you can here its spooled up when you change gear and it will work sometimes?

Also the idle can be a bit lumpy at times.


Registered User
your turbo is a vnt turbo which means that it uses multiple vains within the exhaust housing to adjust the boost pressure the vnt can sometimes stick either open or closed , the only way to really check is to get under the car and try and move the actuator rod to see if its stuck or not ,

here is a vid of how it works VNT turbocharger cutaway animation - YouTube