BoilerFaultCodesYour boiler has detected that the water pressure inside the system is too low to run safely and has stopped working as a result.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Low Water Pressure
What causes this fault?
This fault occurs when the internal water pressure drops below the minimum level required for the boiler to operate safely. The most common reasons are a slow leak from a radiator valve or pipework, or a loss of air pressure in the expansion vessel which helps regulate the water volume.
This fault is frequently seen in autumn when the heating is first turned on after summer, as thermal expansion can highlight existing slow leaks or pressure drops.
DIY fix possible
Locate the filling loop (usually a silver flexible hose with one or two blue handles underneath the boiler).Slowly open the valve or valves until you hear water flowing and watch the pressure gauge.Close the valves tightly once the pressure gauge reaches between 1.0 and 1.5 bar.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F1 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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