BoilerFaultCodesPro AL41 Fault Code
The Pro AL41 fault code means: your boiler has stopped working because the water pressure in the system has dropped too low.. It appears on 1 Pro model in our database.
Technical description: Insufficient system water pressure
DIY fix possible
Locate the filling loop (usually a silver braided hose underneath the boiler).Open the small valve handle(s) slowly to let fresh water into the system.Watch the pressure gauge and close the valves when the needle reaches between 1 and 1.5 bar.
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Pro models that show the AL41 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Pro AL41 fault code information on this page is sourced and cross-checked against the official Pro service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026