BoilerFaultCodesYour boiler has switched itself off because it has gotten too hot, likely due to a circulation issue or a component failure.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Overheat fault - Safety thermostat has activated
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to shut the system down to prevent damage. The most common reasons are a failed pump that isn't moving water away from the heat exchanger quickly enough, or a blockage caused by a build-up of debris and sludge within the system.
This fault is more frequent when you first turn the heating back on for autumn, as pumps can seize up after being idle throughout the summer.
DIY fix possible
Check that all radiator valves are fully openCheck that the boiler pressure is between 1.0 and 1.5 bar on the gaugeWait 30 minutes for the unit to cool down and try pressing the reset button
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F05 — no call-out fees, no surprises.
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