740 quick Q about crank sensor

I am stumped about the intermittent no-start situation of my 780 T16V.
Once the engine starts it will keep on running. But sometimes , usually after i drove the car somewhere else, it refuses to start. Startermotor cranks at good speed. I can hear the fuel pump prime before cranking.

Things i did already:
- resoldered the fuel pump relais
- resoldered the radio suppression relais
both work fine
- i also noticed that the alternator Vbelt was lose and not in good condition so i put on a new one. The tension of the belt is good. Battery is in good condition.

When the no-start condition happens i open the hood, disconnect the crank sensor, reconnect it and usually the engine starts first try. I inspected the connectors, no corrosion. I inspected the signal pickup end, no debris struck to it

Can a crank sensor intermittently stop providing the block signal?
What causes this?

Yes, it can stop providing the signal intermittently. I’ve replaced probably at least 20 of them over the years for that reason. I’ve never dissected want one figure out if there is a bad connection in the leads or what the problem is.

I too have had these cause a no start then you come back later and it starts fine. Volvo updated these things and there is supposed to be a white marker on the updated ones. Although I would still think they can become intermittent. The original ones had a yellow marker on them.

OK, thanks to both for the info, i guess i'll be buying a new one.

update:
i bought a new sensor, brand: Meyle.
Installed it and it seems to be fixed. Engine actually seems to start faster, only 1 full crank rotation (= 4 compressions) needed. With the old sensor it always needed 2 full crank rotations.