BoilerFaultCodesYour boiler has shut down because the water inside it has become too hot, usually due to a lack of circulation or a blockage in the system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow Temp Overheat Lockout
What causes this fault?
This fault occurs when the internal sensors detect that the water is heating up too quickly or has reached a dangerously high temperature. The most common reason is that the water cannot move through the boiler properly, which is often caused by a failed pump, a blockage of sludge in the system, or air trapped within the unit.
This issue is more frequent during the first cold spell of autumn, when the heating is turned on after a long period of inactivity and the pump has seized up.
DIY fix possible
Check that your radiator valves are fully open.Ensure the boiler pressure is between 1 and 1.5 bar on the gauge.Reset the boiler by turning the control knob to 'Reset' and then back to 'On'.
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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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