BoilerFaultCodesYour boiler has shut itself down because it has detected that the water or the exhaust fumes have become too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety Thermostat Activated (Boiler or Flue)
What causes this fault?
This fault occurs when the boiler's internal temperature exceeds safe limits, triggering a safety sensor to cut off the gas supply. The most common reasons are a failed pump stopping water from circulating or a build-up of limescale and sludge creating a blockage that traps heat inside the heat exchanger.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after months of inactivity, as pumps can seize during the summer.
DIY fix possible
Check that your radiator valves are open and not turned to zeroTurn the control knob to the 'Reset' position for five seconds and then back to 'On'Ensure the boiler pressure gauge is between 1 and 1.5 bar
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
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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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