BoilerFaultCodesPotterton neons flashing Fault Code
Also written as NEONSFLASHING — same fault.
The Potterton neons flashing fault code means: your boiler has sensed it is getting too hot and has shut itself down as a safety precaution.. It appears on 2 Potterton models in our database.
Technical description: Overheat thermostat or Flue thermostat operated. Turn selector to reset; if it does not extinguish, check thermostats or sections H and K.
What causes the Potterton neons flashing fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature or the exhaust gases become too hot, triggering a safety sensor to cut the power. The most common reasons are a pump failure preventing water from circulating or a blockage within the heat exchanger that traps heat inside the unit. It can also be caused by a build-up of air pockets or various faulty internal sensors failing to accurately read the temperature.
This issue is more frequent during the first cold snap of autumn when a pump that has been idle all summer suddenly seizes or struggles to move cold, heavy sludge through the system.
DIY fix possible
Check that your radiator valves are open and not turned to zero.Ensure there is enough water pressure indicated on the boiler's pressure gauge (typically 1 to 1.5 bar).Turn the selector switch to the 'Reset' position for five seconds, then turn it back to the 'On' position.
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Gas Safe Register →Potterton models that show the neons flashing fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton neons flashing 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