Vokera Linea He 32 Combi Error code 72?

Hi.
I have a Vokera Linea He 32 Combi boiler…10 years old.
It has started cutting out and giving an error code 72. I have found that when the boiler cuts out and the error code 72 appears, if I should leave the heating and dhw on until the water cools down in the tap again, it does starts up when I press the reset button. If I leave the heating and dhw continually on when this fault is happening and press the reset button each time it cuts out, I sometimes get lucky and it stays on and works ok on both heating and dhw…Until it does it again that is!!
This fault can happen whether I am using the heating and dhw separately or together.
With thanks