BoilerFaultCodesYour boiler has shut itself down because it has reached an internal temperature that is too high to operate safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: OVERHEAT CUT-OFF THERMOSTAT: The appliance will enter a lockout condition in the event of overheating. An overheat cut-off thermostat is fitted to the appliance which will interrupt the electricity supply to the gas valve.
What causes this fault?
This fault occurs when the water inside the boiler gets too hot, causing a safety switch to cut the power and prevent damage. The most common reasons are a pump failure that stops water from moving through the system or a blockage that restricts flow, leading to a rapid heat build-up.
This issue is more frequent in autumn when heating systems are first turned back on, as pumps often seize up after being inactive throughout the summer.
DIY fix possible
Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough water pressure in the system by checking the pressure gauge (aim for 1.5 bar).Press and hold the reset button for five seconds once the boiler has cooled down.
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