Motor doesn't start. Engine Speed Sensor G28

Hi, guys.
Two weeks ago, my ABH didn't want to start. He went into town normally and when I wanted to go home he didn't jump any more. I then checked fuses, scanned relays, from the engine compartment and central electrics, but everything seemed to be complete. After 1 hour of unsuccessful searching for the mistake, he just ran again.
Unfortunately, I had no access to a laptop with which I could read out the error memory, nor the time to deal with it further.

Yesterday, countless starts and kilometers later, he doesn't want to, this time no more.
This time I could read out the error memory: 0513 Engine Speed Sensor (G28) 03-00 No signal.
I'll erase the mistake, ignition, and again the error will come back.

The Conlog immobilizer was my next guess. However, both the petrol relays switched and the pump also gets its voltage. If I don't unlock, the pump won't get any voltage. So the mistake shouldn't be here.

I've got sparks on both benches, so the dog isn't buried here either.

The cables that lead to the sensors are optically not damaged, plug contacts I opened and cleaned up, but did nothing. A wobble to the cable, unfortunately, also not.

What confuses me is the fact that there are many starts between the mistakes and over 400km.

What do you say it's on the sensor, and a swap makes help?