BoilerFaultCodesYour boiler has detected that there is not enough water pressure or the water is not moving through the system properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Faulty primary circuit (no water or absence of flow)
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water isn't moving through the heat exchanger, which could lead to overheating if the burner stays on. The most common reasons are a buildup of sludge blocking the pipes, a mechanical failure of the pump, or simply that the system pressure has dropped too low for the boiler to operate safely.
This issue is more frequent in autumn when heating is first turned on after summer, as pump components can seize up during long periods 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 filling loop underneath the boiler to top it up with water.Ensure all radiator valves are open and that the pump is not blocked or stuck.
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