BoilerFaultCodesYour boiler has overheated, causing it to shut down automatically for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High limit thermostat fault
What causes this fault?
This fault occurs when the internal temperature of the boiler exceeds a safe limit, triggering a safety sensor to cut the power to prevent damage. The most common reasons are a blockage in the system or a pump failure, which stops the water from moving quickly enough to carry heat away from the burner.
This issue often appears during the first cold spell of autumn when the heating is turned back on after months of disuse, which can cause internal parts like the pump to seize.
DIY fix possible
Check that at least one radiator or bypass valve is fully openTurn the selector switch to the 'OFF/RESET' position for 10 secondsTurn the selector switch back to 'ON' and check if the red light stops flashing
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