BoilerFaultCodesYour boiler has switched itself off because it has become too hot internally, usually due to a lack of water flow or a blockage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat error
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, causing the system to shut down for safety. The most common reason is a lack of circulation, often caused by a failing pump or a build-up of sludge and debris blocking the internal pipework. Air trapped within the heat exchanger can also prevent water from absorbing heat correctly, leading to a sudden temperature spike.
This issue is frequently seen when heating is first turned on in autumn, as pumps can seize after being inactive throughout the summer months.
DIY fix possible
Check that your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Ensure all radiator valves are fully open to allow water to circulate.Turn the boiler off and on again to see if the fault clears after cooling down.
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