Did you just install the JB4? Does the car do that if you change to JB4 bypass (Mode 0)?
I would check all of your connections. If that doesn't sort it then I would suggest posting this in the N54 or N55 Technical Forum since there are far more people with the sort of knowledge you seek over there. You don't specify the year of your car so I don't know which engine you have.
This forum is really for things that are specific to the Xi/xDrive, which is mainly suspension and driveline.