Hello colleagues, I wanted to report a solved case on this VAG group motorisation.

This Golf VI shuts down and struggles to start or does not start, glow plug light flashing with errors:

p0642 Sensor reference voltage A: Signal too low

p0335 Crankshaft position sensor: Defective function

p0341 Camshaft position sensor: Implausible signal

the fault is sporadic, so testing the car shows a tear with the glow plug light coming on and in the diagnosis the error p0642: Reference voltage A, consulting the wiring diagram the problem can be traced back to a voltage drop (or short to ground) of the 5v power supply circuit that reaches the following components: V157 engine swirl, g581 turbo vgt position sensor, g212 egr potentiometer, g247 rail fuel pressure sensor, j338 intake manifold throttle and g40 camshaft hall sensor.

After several tests looking for the fault on the various components, the short to earth was found to be on the engine harness, in fact the short to earth was found near the harness going up to the injectors, between the depressor and the swirl actuator motor.

Bear in mind that the wiring harness in question is the one going up to the injectors, glow plugs and rail pressure sensor, passing through the cable duct on the tappet cover, so errors and faults can be of various kinds.

attached some photos

Greetings!