While you wait for answers, we may have found some information which could help you.
Click here for Reset Combi BoilerSaunier Duval Isofast condens F35E....nothing working?
How can I fix my Saunier Duval Semia Condens boiler?
saunier duval boiler problem?
'f19' error report - Saunier Duval 'Thermoclassic' boiler?
Saunier Duval timeclock not working?
How to repair F4 code?