BoilerFaultCodesSaunier Duval F1 or F4 Fault Code
Also written as F1ORF4 — same fault.
The Saunier Duval F1 or F4 fault code means: your boiler is failing to light the internal flame needed to produce heat and hot water despite several attempts.. It appears on 2 Saunier Duval models in our database.
Technical description: Ignition fault
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Saunier Duval models that show the F1 or F4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Saunier Duval F1 or F4 fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026