Vaillant gas boiler pump continues to run

[alinstroe16]

Hello everyone and thank you in advance for your advices!
I have in my house an old vaillant boiler which was instaled from the previous owner .
The gas boiler is a Vaillant VCW 195/3-C-HL.
The boiler works pretty good but the only issue is that after the heating cycle, when the room temperature is reached and the room thermostat send the signal to the boiler to stop heating, the boiler stops with an exception, the pump will run for hours with the pump sign on the screen even if the water reaches like 20-24 degrees it wont stop.
The single way I could stop the pump is to start hot water or to take the boiler from the power source and then plug it back in.
I will attach some photos with the pcb and the gas boiler.

 

[Stuckinarut]

Could be a stray voltage or if it has a pump proving switch, could be stuck?

 

[timbo29]

I've gone into installer level on mine and there appears to be a test programme which keeps the pump running

 

[alinstroe16]

Thank you for your adices, I checked the voltage between N and G and is 0.5 v and between boiler case and N is the same, 0.5 v, is this the problem?
And about the pump proving switch , it does not have something like that.

About the test program, I do not know what is that, could be deactivated?

What I noticed today is that, if I turn the heating on for maximum 2 or 3 seconds and then turn the heating off imediately the pump will stop.
But if I leave it on more than 3 seconds until the fan will kick in, then the pump will run and I cant stop it only if I get the power out.