BoilerFaultCodesFerroli FD Fault Code
The Ferroli FD fault code means: your boiler has detected that the internal temperature is very low and is running its pump to prevent the water inside from freezing.. It appears on 1 Ferroli model in our database.
Technical description: Anti-freeze protection device is in operation
DIY fix possible
Ensure your boiler is switched on and the power supply is activeKeep your heating thermostat set to a level that prevents the ambient temperature from dropping too lowWait for the temperature to rise, at which point the code should disappear automatically
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Ferroli models that show the FD fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli FD 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 7 July 2026