BoilerFaultCodesYour boiler has shut down because the water inside it has become too hot, usually due to a lack of water flow or 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 Temp Overheat Lockout
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit and cannot be cooled down quickly enough. The most common reasons are a pump failure preventing the water from moving or a blockage within the pipework that restricts flow. In some cases, it can also be triggered by a faulty sensor giving a false reading to the boiler's control board.
This fault is frequently seen at the start of autumn when heating systems are turned on for the first time after summer, often because the pump has seized due to inactivity.
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 bar on the front gauge.Ensure all radiator valves are fully open and not turned off.Reset the boiler by turning the mode dial to 'reset' for two seconds and then back to your desired setting.
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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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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