I have just seen one logging this fault code so the other garage replaced the turbo and then sent it to us.
It was still logging the same fault code and the sensor feedback voltage looked OK by checking at the sensor with a scope or multimeter 0.5V - 4.5v

When looking at Position feedback on IDS or Maxidas Both showed the voltage fluctuation FROM -115v to + 150v.

We suspected either a wiring fault back to the ecu or a faulty ecu but the customer didn't want to carry on so we never got to the bottom of the problem.

HTH. Tony.