Can anyone offer advice, Ive recently bought a Mazda 3 2011, 1.6 diesel. When I drive the car and what I assume to be the boost of the turbo starting to work, I can hear what id describe as high pitched whine, coming from behind the dash on the drivers side which correlates to when the turbo works.
Im guessing there must be an air line to the dash for a boost gauge which may have a leak causing the noise but cant see any such gauge in the car, has anyone else had this issue, if so , how do I fix it please.

 

No air or vacuum lines. Possibly the noise of the turbo/induction system is penetrating the cabin.