BoilerFaultCodesYour boiler has stopped working because it cannot detect water moving through the system to keep it running safely.
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.
What causes this fault?
This fault occurs when the boiler's internal sensors do not detect any water movement after the pump has started. The most common cause is a seized or failing circulation pump that is no longer able to push water through the heat exchanger, but it can also be triggered by severe air locks or a total blockage in the heating circuit.
This fault is more frequent in autumn when the heating is turned back on after a long summer break, as pumps often seize up during periods of inactivity.
DIY fix possible
Check that your external heating valves or isolation valves are fully open.Ensure your radiator valves (TRVs) are turned up and not all closed.Check the boiler pressure gauge and top it up to 1.5 bar if it is too low.Gently bleed your radiators to remove any trapped air pockets.
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A boiler cover plan would cover faults like Fd — 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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