BoilerFaultCodesYour boiler has switched itself off because it has detected that it is getting too hot or a temperature sensor has failed.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat thermostat has operated / Temperature sensor fault
What causes this fault?
This fault occurs when the water inside your boiler reaches a temperature that is dangerously high, causing the system to shut down for safety. The most common reasons are a pump failure that prevents heat from moving away from the boiler, or a internal sensor that has become faulty and is sending incorrect readings to the control board.
This issue is more frequent during the first cold snap of winter when central heating is turned back on after months of inactivity, which can cause internal pumps to seize up.
DIY fix possible
Check that your radiator valves are open to allow water to flowCheck that your system pressure is between 1 and 1.5 bar on the gaugeTurn the selector switch to the 'Reset' position for a few seconds and then back to 'On'
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like Flashing red A or B — no call-out fees, no surprises.
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Alpha Flashing Light 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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