BoilerFaultCodesYour boiler has shut down because it is getting too hot inside, likely because water isn't moving through the system properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Heat exchanger blocked or pump failure (Overheat)
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety shutdown to prevent damage. The most common reason is that the water is not circulating correctly, often because the pump has seized or the heat exchanger is restricted by a buildup of debris and sludge.
This issue is more frequent when the heating is first switched on after summer, as the circulation pump can seize up after long periods of inactivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F3 — no call-out fees, no surprises.
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