BoilerFaultCodesPotterton neon flashing Fault Code
Also written as NEONFLASHING — same fault.
The Potterton neon flashing fault code means: your boiler has detected that the water temperature has got too hot and has shut itself down as a safety precaution.. It appears on 4 Potterton models in our database.
Technical description: Go to section 'B'
What causes the Potterton neon flashing fault?
This fault occurs when the water inside the heat exchanger reaches a dangerously high temperature, triggering a safety switch to cut the power. It is usually caused by a lack of water flow, often due to a failed internal pump or a blockage in the system preventing the heat from escaping. In some cases, the thermostat itself may have become faulty and is reporting an incorrect temperature reading.
This issue often surfaces during the first cold snap of autumn when the heating is turned on after being idle all summer, which can cause internal parts like the pump to seize.
DIY fix possible
Wait for the boiler to cool down completely (at least 20 minutes)Turn the selector switch to the 'Reset' position and hold for 5 secondsTurn the selector switch back to the 'Hot Water' or 'Heating' positionCheck that your radiator valves are open and the system pressure is between 1 and 1.5 bar
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Gas Safe Register →Potterton models that show the neon flashing fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton neon 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