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: There is insufficient water in your system.
What causes this fault?
This fault occurs when the internal sensors detect that the water pressure has dropped below the minimum level required to protect the heat exchanger from overheating. The most common reason is a slow leak somewhere in your radiator network or a problem with the expansion vessel which helps manage pressure changes. In some cases, it may simply be that you have recently bled your radiators and haven't topped up the system water afterwards.
This fault is more common in autumn when homeowners turn their heating back on for the first time, as small leaks often develop while the system sits idle over summer.
DIY fix possible
Locate the silver braided filling loop hoses underneath or near your boilerSlowly open the one or two small taps on the filling loop to allow water into the systemMonitor the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps tightly
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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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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