BoilerFaultCodesPotterton Water Circulation LOCKOUT Fault Code
Also written as WATERCIRCULATIONLOCKOUT — same fault.
The Potterton Water Circulation LOCKOUT fault code means: your boiler has switched itself off because it has detected that water is failing to move through the system correctly, causing it to overheat.. It appears on 2 Potterton models in our database.
Technical description: Manual Lockout. Activated if flow direction is incorrect or casting thermistor exceeds 80C four times. Check system water level, pump, and bypass.
What causes the Potterton Water Circulation LOCKOUT 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.
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Gas Safe Register →Potterton models that show the Water Circulation LOCKOUT fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Water Circulation LOCKOUT fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026