BoilerFaultCodesYour boiler has stopped working because the water pressure inside the system has dropped too low 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: Indicates the system pressure is approaching zero or is below the minimum required 0.7 bar.
What causes this fault?
This fault occurs when the internal water pressure drops so low that the boiler can no longer circulate heat safely. The most common reasons are a slow leak hidden somewhere in your pipework or radiators, or a component like the expansion vessel losing its ability to regulate pressure over time.
This issue is frequently seen in autumn when the heating is turned on for the first time after summer, often due to air trapped in the system or small leaks that developed while the unit was idle.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Open the valves slowly until you hear water flowing and watch the pressure gauge needle move.Close the valves tightly once the pressure 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 Red 'Low Pressure' light (flashing) — no call-out fees, no surprises.
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Glow-worm Swift Flow 100 is discontinued — time for a new one?
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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