BoilerFaultCodesYour boiler has switched itself off because it has detected that water is failing to move through the system correctly, causing it to overheat.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Lockout Burner Mains - Manual Water Circulation LOCKOUT (Activated if casting thermistor exceeds 80C 4 times or flow direction is incorrect)
What causes this fault?
This fault occurs when water cannot travel through the boiler fast enough to carry heat away, causing the internal components to get too hot. This is usually caused by a failing pump that can no longer push the water, or a buildup of sludge and debris creating a blockage within the system.
This issue often surfaces in autumn when the heating is turned back on for the first time, as the pump can seize up after sitting idle throughout the summer.
DIY fix possible
Check that all radiator valves are open and not turned off.Ensure your system water pressure is within the green zone (typically 1.0 to 1.5 bar).Press the reset button to see if the fault clears after the system has cooled down.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like Water Circulation LOCKOUT — no call-out fees, no surprises.
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Potterton Performa SL HE 9 2 is discontinued — time for a new one?
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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