BoilerFaultCodesYour boiler is overheating because the water is not flowing through the system as quickly as it should.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High-temperature difference
What causes this fault?
This fault occurs when the water inside the boiler heats up too quickly because it isn't being moved away into your radiators fast enough. The most common reasons are a failing external pump, a blockage in the pipework, or a buildup of debris and limescale inside the heat exchanger that restricts water flow.
This issue often surfaces in autumn when the heating is turned back on after a long summer break, as external pumps can seize up during periods of inactivity.
DIY fix possible
Check that all radiator valves (TRVs) are fully openEnsure the external system pump is running and hasn't seizedCheck for any blockages in the system filters
Find a Gas Safe engineer
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A boiler cover plan would cover faults like 45 — 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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