BoilerFaultCodesFerroli A41 Fault Code
The Ferroli A41 fault code means: your boiler has lost communication with the internal sensor that monitors water temperature, meaning it cannot safely heat your home or water.. It appears on 7 Ferroli models in our database.
Technical description: Flow sensor error – sensor disconnected
What causes the Ferroli A41 fault?
This fault occurs when the boiler's main control board loses the electronic signal from the sensor that monitors the temperature of the water leaving the unit. The most common reason is that the sensor itself has developed an internal electrical failure, or the wiring connecting the sensor to the control board has become loose or damaged.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ferroli models that show the A41 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli A41 fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026