BoilerFaultCodesYour boiler has likely stopped heating because it has reached an unusually high internal temperature and has shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Is there 240V~ between yellow connection on overheat device and 10? Check overheat reset. If satisfactory replace overheat device.
What causes this fault?
This fault occurs when the boiler's internal water temperature exceeds a safe limit, triggering a safety sensor to cut the power. It is often caused by a failing pump that isn't circulating water quickly enough or a buildup of sludge and debris blocking the heat exchanger. The system shuts down completely to prevent internal components from melting or warping due to excessive heat.
This issue often surfaces during the first cold spell of autumn when the heating system is turned on after being dormant all summer, which can cause stuck pumps to fail.
DIY fix possible
Wait for the boiler to cool down completely.Locate the overheat reset button on the control panel or underside of the unit.Press the reset button firmly to see if the boiler restarts.
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