BoilerFaultCodesHeatline F0 Fault Code
The Heatline F0 fault code means: your boiler has detected that the water pressure is outside the safe operating range, causing the system to shut down to prevent damage.. It appears on 3 Heatline models in our database.
Technical description: The Water Pressure is TOO LOW or TOO HIGH
DIY fix possible
Locate the pressure gauge on the front of the boiler to see if it is below 1.0 bar or above 3.0 bar.If the pressure is too low, use the filling loop handles underneath the boiler to slowly top it up until the gauge reads between 1.0 and 1.5 bar.If the pressure is too high, bleed a radiator using a radiator key to release water and lower the pressure back to 1.5 bar.Once the pressure is corrected, restart the boiler to clear the fault.
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Heatline models that show the F0 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Heatline F0 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