BoilerFaultCodesHeatline Bar LED Flashing Fault Code
Also written as BARLEDFLASHING — same fault.
The Heatline Bar LED Flashing fault code means: your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.. It appears on 2 Heatline models in our database.
Technical description: Low water pressure (Check pressure gauge show >1 bar / Repressurise system)
DIY fix possible
Locate the external filling loop, which is usually a small metal braided hose underneath the boiler.Slowly open the valve(s) on the filling loop to allow water to enter the system until the pressure gauge reads between 1 and 1.5 bar.Close the valve(s) tightly and restart your boiler.
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Gas Safe Register →Heatline models that show the Bar LED Flashing fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Heatline Bar LED Flashing fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026