Problem Stopped in motion


I have a problem with Audi a4 b7 2.0tdi BPW, MULTITRONIC. For a few days, when starting it started to hear for a second a metallic noise/trembling, as if the steering wheel or the electric motor were stuck. Today it stopped running and did not start again. On VAG-COM, there is no error of any kind, neither with the engine nor with the box. What problem could he have? Is it possible that the car won't start because of the steering wheel? I mention that the tank pump draws diesel. Thanks!