BoilerFaultCodesYour boiler is struggling to move water through the system, which is causing it to stop running to prevent overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Circulation Fault (Primary Circuit)
What causes this fault?
This fault occurs when water is unable to circulate through your boiler's internal pipework fast enough, leading to a rapid rise in temperature. The most common reason is a failing pump that can no longer push the water, though a blockage caused by a build-up of sludge or a stuck internal valve can also restrict the flow. To prevent internal damage from overheating, the boiler safety system shuts the unit down completely.
This fault is more common in autumn and winter when the heating is first switched back on after several months of inactivity, as pumps can seize during long periods of disuse.
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barTry resetting the boiler to see if the fault clears
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A boiler cover plan would cover faults like E125 — no call-out fees, no surprises.
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