Hi Aamir,
The fault codes given on the German forum indicate either a clutch or gearbox problem. The G38 sensor measures the speed of the output shaft of the gearbox and this is compared with the engine revs. If this ratio is outside a certain tolerance, it is assumed that the clutch is slipping and the system effectively shuts down, putting the car in neutral and disabling the throttle.
You can check for clutch bearing/guide sleeve failure by carrying out a transmission basic setting, noting the clutch voltage value. Repeat the operation, again noting the clutch value. If the two values differ by more than 0.05v, this is indicative of clutch bearing and/or guide sleeve failure.
Also some (?) ANY gearboxes are known to have been assembled with excessive preload on the output shaft bearing, leading to eventual failure. This gives rise to excessive clearance between the G38 and the gear that it is monitoring, resulting in it failing to work, with consequent shutdown. The G38 is a Hall effect sensor and is unlikely to fail.
RAB