BoilerFaultCodesYour boiler has switched itself off because it has reached an internally high temperature and needs a manual restart to clear the safety lock.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Should the appliance not light, check it is not in the overheat lock-out state, by pressing the re-set button on bottom right hand side of the control box.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety switch to prevent damage. The most common reasons are a pump failure that stops water from moving through the system or a build-up of debris blocking the internal heat exchanger. It can also be caused by a faulty sensor misreading the temperature even if the boiler isn't actually too hot.
This fault is more common in autumn when heating systems are turned back on after a long summer break, often revealing a circulation pump that has seized during the idle months.
DIY fix possible
Locate the control box on the boiler unitIdentify the reset button on the bottom right-hand sidePress and hold the button for a few seconds to clear the lock-outCheck that your radiator valves are open to allow water to circulate
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A boiler cover plan would cover faults like overheat lock-out state — no call-out fees, no surprises.
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