BoilerFaultCodesJohnson Starley F37 Fault Code
The Johnson Starley F37 fault code means: your boiler has stopped working because the water pressure in the central heating system has dropped too low.. It appears on 2 Johnson Starley models in our database.
Technical description: Central heating water pressure fault
DIY fix possible
Locate the metal braided filling loop underneath or near your boiler.Slowly open the one or two valves on the loop until you hear water flowing.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves tightly.
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Johnson Starley models that show the F37 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Johnson Starley F37 fault code information on this page is sourced and cross-checked against the official Johnson Starley service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026