BoilerFaultCodesYour boiler has shut down because the water inside it has become too hot, likely due to a circulation problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow temperature overheat
What causes this fault?
This fault occurs when the water leaving your boiler exceeds a safe temperature limit, causing the system to shut down for safety. It is typically caused by a blockage in the pipework, a failing pump that cannot move the water quickly enough, or a build-up of debris known as sludge.
This issue often surfaces during the first cold spell of autumn, when the heating system is switched back on after being idle and internal components like the pump may have seized.
DIY fix possible
Check that your radiator valves are fully open to allow water to flow.Ensure your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Press the 'Reset' button on the boiler control panel once the unit has cooled down.
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 L1 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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