BoilerFaultCodesYour boiler has stopped working because the water pressure is too low for it to operate safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The water pressure falls below 0.3 bar. The unit switches off. Fill the system up with water before you start up the appliance again.
What causes this fault?
This fault occurs when the internal water pressure drops so low that the boiler can no longer safely transfer heat from the burner to the water. The most common reasons are a slow leak hidden somewhere in your pipework or radiators, or the pressure being accidentally released through a safety valve.
This fault is frequently seen in autumn when homeowners turn their central heating back on for the first time, as the sudden heat can expose small leaks or issues with the expansion vessel.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Slowly open the valve(s) until you hear water entering the system.Watch the pressure gauge and close the valves once the needle reaches between 1.0 and 1.5 bar.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F.22 — 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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