BoilerFaultCodesYour boiler has detected that water is circulting too slowly or there is not enough water pressure to run safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Clas Net one CombiClas one CombiClas System one
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water isn't moving through the system quickly enough to carry heat away from the burner. The most common reasons are a pump that has seized or slowed down, a blockage caused by sludge in the pipework, or a lack of sufficient water pressure to allow proper circulation.
This issue is frequently seen when the heating is first turned on after summer, as the circulation pump can seize 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 carefully.Ensure all radiator valves are fully open and check for any visible leaks around the pipework.
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A boiler cover plan would cover faults like 1p4 — 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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