BoilerFaultCodesSaunier Duval F12 Fault Code
The Saunier Duval F12 fault code means: your boiler's internal computer has lost communication with the control panel or display, preventing the system from operating.. It appears on 5 Saunier Duval models in our database.
Technical description: Main board connection fault
What causes the Saunier Duval F12 fault?
This fault occurs when the boiler's main brain and the front display panel stop talking to each other due to an electrical communication break. The most common reasons are a loose internal plug, moisture getting onto the electronics, or a component failure on one of the circuit boards themselves.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Saunier Duval models that show the F12 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Saunier Duval F12 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 27 April 2026