BoilerFaultCodesYour boiler has switched itself off because it has become too hot to operate safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Boiler is not working for central heating or hot water and the display shows ‘LLLLL:::::AAAAA ’ (flashing). Indicates an overheat condition.
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety shutdown to prevent internal damage. The most common reasons are a pump failure that stops water from moving or a blockage in the pipework that traps heat inside the unit.
This issue often appears when the heating is turned on for the first time in autumn, as internal pumps can seize up after being inactive throughout the summer.
DIY fix possible
Check that all radiator valves are fully open and not turned off.Ensure there are no obstructions around the boiler's external vents.Turn the boiler off and back on again to attempt a system reset.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like A — no call-out fees, no surprises.
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