BoilerFaultCodesFerroli 5 (Flashing Light) Fault Code
Also written as 5FLASHINGLIGHT — same fault.
The Ferroli 5 (Flashing Light) fault code means: your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.. It appears on 9 Ferroli models in our database.
Technical description: Insufficient pressure in Central Heating System
DIY fix possible
Locate the filling loop, which is usually a flexible silver hose with one or two valves typically found underneath your boiler.Open the valves slowly to allow water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close both valves tightly to prevent over-pressurisation and check your radiators for any visible leaks.
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Gas Safe Register →Ferroli models that show the 5 (Flashing Light) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli 5 (Flashing Light) 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