BoilerFaultCodesPotterton Neon9 Fault Code
Also written as NEON9 — same fault.
The Potterton Neon9 fault code means: your boiler has detected that a temperature sensor is not working correctly, meaning it cannot accurately measure how hot the water is.. It appears on 1 Potterton model in our database.
Technical description: Fault on Temperature Sensor
What causes the Potterton Neon9 fault?
This fault occurs when the boiler's control board loses communication with the internal temperature sensor, often because the component has suffered electrical failure or chemical degradation over time. The most common reason is that the sensor has become 'scaled up' or the internal thermistor has worn out, preventing it from sending a reliable signal to the boiler.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the Neon9 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Neon9 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