BoilerFaultCodesKeston F1 Fault Code
The Keston F1 fault code means: your boiler has detected that the water pressure in the system is too low to run safely and has shut down as a precaution.. It appears on 3 Keston models in our database.
Technical description: Low water pressure
DIY fix possible
Locate the metal braided filling loop underneath or near the boiler.Slowly open the small handles on the valves until you hear water entering the system.Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.
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Keston models that show the F1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston F1 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026