BoilerFaultCodesFerroli A56 Fault Code
The Ferroli A56 fault code means: your boiler is having trouble setting up its gas and air mixture correctly, which prevents it from firing up safely.. It appears on 3 Ferroli models in our database.
Technical description: Calibration error / calibration procedure not completed
What causes the Ferroli A56 fault?
This fault occurs when the boiler's internal computer is unable to verify that the gas and air are mixing in the correct proportions for a safe flame. It is usually triggered because the sensors aren't detecting a consistent signal during the start-up phase or the gas valve isn't responding correctly to the calibration commands. This prevents the boiler from firing up to ensure no unburnt gas or dangerous fumes are produced.
DIY fix possible
Check that your gas supply is turned on and other gas appliances are workingPress and hold the 'Reset' button for 5 seconds to clear the faultAllow the boiler to attempt its automatic calibration sequence for several minutes
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Gas Safe Register →Ferroli models that show the A56 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli A56 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