Hi Saar,
I've got the TD5 D2 and the bags fail on these all the time. Best way to check is put in offroad mode to fully inflate and then go over the whole system with soapy water and listening for leaks in the bags and pipes where they rub on the metal parts.
Also, as suggested above, in cold weather the intake filter can freeze if it gets wet.
Sorry I can't be more specific as I don't know the D3s that well.
Griff