That didn't really answer my question. I am aware of the common fault with the old PCBs, but as you will see from my original post, the boiler has had an upgrade kit fitted.
What is an APS?
Thanks
I've got a Suprema 60L with an updated PCB in the Siemens grey plastic housing. I've realised that the boiler is turning itself off after running for a few minutes. It displays a green flashing light after I hear the fan turn off, then after a minute or so a relay clicks and the light turns...