BoilerFaultCodesYour boiler has sensed it is getting too hot and has shut itself 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: Overheat thermostat or Flue thermostat operated. Turn selector to reset; if it does not extinguish, check thermostats or sections H and K.
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature or the exhaust gases become too hot, triggering a safety sensor to cut the power. The most common reasons are a pump failure preventing water from circulating or a blockage within the heat exchanger that traps heat inside the unit. It can also be caused by a build-up of air pockets or various faulty internal sensors failing to accurately read the temperature.
This issue is more frequent during the first cold snap of autumn when a pump that has been idle all summer suddenly seizes or struggles to move cold, heavy sludge through the system.
DIY fix possible
Check that your radiator valves are open and not turned to zero.Ensure there is enough water pressure indicated on the boiler's pressure gauge (typically 1 to 1.5 bar).Turn the selector switch to the 'Reset' position for five seconds, then turn it back to the 'On' position.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like neons flashing — no call-out fees, no surprises.
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Potterton Performa 24 Eco HE 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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