BoilerFaultCodesHeatline F1 Fault Code
The Heatline F1 fault code means: your boiler has switched itself off because it has reached an unsafe temperature and needs to cool down before it can be restarted.. It appears on 7 Heatline models in our database.
Technical description: Lockout due to overheating. This may be the overheat thermostat or thermal fuse.
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1 and 1.5 bar on the gaugePress the reset button once the boiler has cooled down for 20 minutes
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Heatline models that show the F1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Heatline F1 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 31 August 2026