Worcester Bosch help

[Ayy Bee]

I have a greenstar 35cdi combi boiler that when the thermostat calls for heat. It will fire up heat to temp and then drop down to 41* on the boiler display and then kick back in again.

I have checked all wiring and the zone valves. What else could it be? anyone seen this before

 

[Nicholas]

I have the exact same issue so keen to know if you find a solution