BoilerFaultCodesYour boiler is overheating because water isn't moving through the system fast enough, causing it to shut down to prevent damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water temperature rising too quickly
What causes this fault?
This fault occurs when the water inside the boiler heats up far too quickly, triggering a safety sensor to prevent the unit from melting or cracking. The most common reason is a blockage or a failed pump preventing the water from flowing out of the boiler and into your radiators. It can also be caused by a build-up of sludge or debris in the system that acts like a dam, trapping heat inside the heat exchanger.
This fault is most common when turning the heating on for the first time in autumn, as circulation pumps can seize up after being inactive all summer.
DIY fix possible
Check that all radiator valves are fully openEnsure your central heating bypass valve (if visible) is openTry resetting the boiler to see if the fault clears
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A boiler cover plan would cover faults like F24 — no call-out fees, no surprises.
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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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