BoilerFaultCodesYour boiler has become too hot and has shut itself down for safety 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: Appliance overheat
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, causing the system to shut down to prevent internal damage. The most common reasons are a pump failure that stops water from moving or a blockage in the heat exchanger that restricts flow. It can also be triggered by a build-up of air or sludge within the pipework that prevents heat from being carried away from the burner.
This issue often appears when the heating is first turned on after summer, as the internal pump can seize up after long periods of inactivity.
DIY fix possible
Check that all radiator valves are fully openEnsure the system pressure is between 1 and 1.5 barPress the 'Reset' button on the control panelWait 20 minutes for the unit to cool down before trying to restart
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E12 — 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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