BoilerFaultCodesYour boiler has switched itself off because it has gotten too hot, likely due to a blockage or a pump issue stopping the water from circulating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: OVERHEAT
What causes this fault?
This fault occurs when the internal temperature of the boiler exceeds a safe limit, causing the safety sensors to shut the system down instantly. The most common reason is that the water isn't moving through the unit quickly enough to carry the heat away, often due to a failed pump or a build-up of sludge blocking the pipes. In some cases, a faulty sensor may also be misreading the temperature and triggering a false alarm.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on and a pump that has been idle all summer fails to start.
DIY fix possible
Check that your radiator valves are fully open to allow water flowEnsure there is enough water pressure in the system (check the gauge)Press the reset button once the boiler has cooled down
Find a Gas Safe engineer
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A boiler cover plan would cover faults like LOCKOUT: b — no call-out fees, no surprises.
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Potterton Housewarmer is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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