BoilerFaultCodesFerroli F41 Fault Code
The Ferroli F41 fault code means: your boiler has shut down because the temperature difference between the water going out and coming back is too high, meaning water isn't moving through the system fast enough.. It appears on 6 Ferroli models in our database.
Technical description: Activation of maximum ELTA T protection
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barBleed all radiators to remove trapped airReset the boiler using the selector switch
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Ferroli models that show the F41 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli F41 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 31 August 2026