BoilerFaultCodesYour boiler is trying to work but cannot detect enough water moving through the system 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: pump has run dry
What causes this fault?
This fault occurs when the boiler's internal pump is spinning but is unable to move water through the heat exchanger. The most common reasons are a lack of water pressure in the system, a large pocket of air trapped inside the pump, or a physical failure of the pump motor itself.
This fault often appears in autumn when the heating is turned back on for the first time, as pump components can seize or become stuck during months of inactivity.
DIY fix possible
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is too low, use the internal or external filling link to top up the system water.Ensure all radiator valves and isolation valves under the boiler are fully open.Restart the boiler using the reset button once the pressure is corrected.
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A boiler cover plan would cover faults like A1 — no call-out fees, no surprises.
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Worcester Bosch Greenstar 25HE 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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