While you wait for answers, we may have found some information which could help you.
Click here for Water Saunier DuvalSaunier Duval timeclock not working?
Saunier Duval Isofast condens F35E....nothing working?
Saunier Duval Thema F23 anyone have a link for manual?
isotwin condens f 35 e service menu codes?
saunier Duval is over pressurising when the heating is on. ?
How to repair F4 code?