BoilerFaultCodesPotterton Section J (Neon Flashing) Fault Code
Also written as SECTIONJNEONFLASHING — same fault.
The Potterton Section J (Neon Flashing) fault code means: your boiler has got too hot and has automatically shut down to prevent damage.. It appears on 1 Potterton model in our database.
Technical description: Overheat thermostat operated or faulty. Allow to cool. Check continuity across thermostat terminals.
What causes the Potterton Section J (Neon Flashing) fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety switch to kill the flame. The most common reasons are a pump failure preventing heat from being carried away or a build-up of sludge and debris blocking the internal pipework.
This fault is more common in autumn when heating systems are first turned back on, as pumps can seize up after being inactive throughout the summer.
DIY fix possible
Ensure all radiator valves are fully open to allow water to circulate.Let the boiler cool down for 30 minutes.Turn the control knob to the 'Reset' position for five seconds, then turn it back to 'On'.
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Gas Safe Register →Potterton models that show the Section J (Neon Flashing) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Section J (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