Hello,
The car is GolfIV/1.9TDI/AXR with a bad starting issue ...
For the first time was readed the fault codes:4141-Rpm sensor-signal improbable.
N28 was replaced,no improvement on the car.
Removing again the sensor and inspecting with a endoscope camera the sensor rotor from crankshaft I can't see any broken/bented part what can explain the strange signal from RPM sensor(image 0001 attached).
Again the wires between engine speed sensor and ECU was checked-no short or open circuit was found.
Measuring the signal from engine speed sensor disconnected I see a clean and big signalthan in image 0001(image 0002 attached)!
Replacing the ECU I solved the issue
Best regards