BoilerFaultCodesJohnson Starley 37 Fault Code
The Johnson Starley 37 fault code means: your boiler has stopped working because the amount of water inside your heating system has dropped below the minimum level required to operate safely.. It appears on 1 Johnson Starley model in our database.
Technical description: Low system water pressure, Water pressure low or sensor failed.
DIY fix possible
Locate the external filling loop, usually a small silver braided hose with one or two valves located underneath the boiler.Gradually open the valve(s) to allow mains water into the system while watching the pressure gauge on the front of the boiler.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then ensure the valves are fully closed.
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Johnson Starley models that show the 37 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Johnson Starley 37 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