While you wait for answers, we may have found some information which could help you.
Click here for Central Heating Hot Water Air Pressure Switch
F40 fault?
Ferolli Optimax HE 31C expansion vessel change?
i have a ferroli combi boiler i have 1/2 the radiators working and 1/2 not ?
How can i repair a noCN fault on my boiler?
Replace a diverter valve?
How turn off heating in Ferolli Optimax 31c?