Hello together, In icy cold, my 635D started to rush a few days ago when the turbo (depending on the gas pedal position from ~60 KmH) started to operate – thought first the front window ventilation at the driver’s side would be more adjusted at once (that’s how it sounded), but it comes out of the engine compartment when listening more closely, tending to go up on the driver’s side. I then passed on leisurely (with ~120 KmH gliding is no problem), but as soon as you try to retrieve power it rushes and from d After a while, a very quiet high whistle set in when driving leisurely. The workshop has now looked very carefully at the whole thing: all hoses are tight (under load you can see them bloating too), both turbochargers build up pressure, charge air cooler also seems OK, but the DPF gives way to high counter pressure and has too high mass (although the BC has nothing to do with it). It should be noted that this DPF was professionally cleaned (burned out, etc.) about 1 year ago (after the BC had indicated this) and reinstalled with new equivalent counterpressure and mass values. Now the obvious measure would be to install a new DPF, cost point ~2K. However, the question arises why the DPF is to be returned after a year. One thesis is that the biturbo loses minimal oil, which is not noticed as a defect, but is added to the DPF. This means that new loaders would also be necessary, cost point including installation ~2.5K. But is it good then? Of course you don’t know that, so you prefer to ask in advance: Does someone have similar experiences behind them and can comment on the theses / considerations? Thank you and greetings