BoilerFaultCodesYour boiler is struggling to move heated water through the system, causing it to shut down 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: Poor circulation
What causes this fault?
This fault occurs when the water inside your boiler gets too hot too quickly because it isn't being pushed around your radiators fast enough. The most common reasons are a pump that has seized up or a build-up of sludge and debris that is physically blocking the pipework. Because the heat has nowhere to go, the boiler forces a shutdown to protect its internal components from heat damage.
This issue often surfaces in autumn when the heating is turned back on for the first time, as internal pump parts can seize up after sitting idle during the summer months.
DIY fix possible
Check that the boiler pressure is between 1.0 and 1.5 bar on the gaugeEnsure all radiator valves are fully openBleed your radiators to remove any trapped air pockets
Find a Gas Safe engineer
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A boiler cover plan would cover faults like E109 — 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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