BoilerFaultCodesAlpha E11 Fault Code
The Alpha E11 fault code means: your boiler has detected that the water pressure is too low for the system to operate safely.. It appears on 1 Alpha model in our database.
Technical description: Primary water pressure switch open
DIY fix possible
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.Locate the filling loop (usually a silver flexible hose) under the boiler.Slowly open the valves until you hear water entering and the gauge rises to 1.5 bar, then close them tightly.
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Gas Safe Register →Alpha models that show the E11 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha E11 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026