BoilerFaultCodesYour boiler has stopped working because it cannot detect water moving through the pipes properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No water flow is detected for 60 secs and the temperature is less than 40ºC. Check system water levels, isolation valves, pump, and water flow sensor.
What causes this fault?
This fault occurs when the boiler's internal computer tries to start the heating process but cannot detect any movement of water through the system. The most common reasons are a pump that has seized up or failed, air being trapped within the unit, or a physical blockage that is preventing the water from circulating correctly.
This issue is more frequent in autumn when the heating is turned back on for the first time after summer, as the internal pump can often stick during long periods of inactivity.
DIY fix possible
Check that the central heating pressure gauge is between 1 and 1.5 barEnsure all radiator valves and boiler isolation valves are fully openGently bleed your radiators to remove any trapped air pockets
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 No Water Flow — 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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