BoilerFaultCodesFerroli A55 Fault Code
The Ferroli A55 fault code means: your boiler's internal computer has encountered a critical electronic failure and can no longer control the heating or hot water safely.. It appears on 3 Ferroli models in our database.
Technical description: Printed circuit board (PCB) AGC01 fault
What causes the Ferroli A55 fault?
This fault occurs when the boiler's main control board suffers a hardware malfunction or a breakdown in electronic communication. The most common reason is a component failure on the circuitry itself or an electrical short caused by wear and tear or moisture ingress over time.
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 A55 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli A55 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