While you wait for answers, we may have found some information which could help you.
Click here for Pressure Gauge Needlesaunier duval boiler problem?
Saunier Duval Isofast condens F35E....nothing working?
'f19' error report - Saunier Duval 'Thermoclassic' boiler?
How to repair F4 code?
Saunier Duval F35E auto-vents down to code 21 in minutes?
isotwin condens f 35 e service menu codes?