neon flashing (Section J/M) High

Potterton neon flashing (Section J/M) Fault Code

Also written as NEONFLASHINGSECTIONJM — same fault.

The Potterton neon flashing (Section J/M) fault code means: your boiler has automatically turned itself off because it has detected that it is running too hot, possibly due to a blockage in the airflow or a problem with the internal water circulation.. It appears on 1 Potterton model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Overheat thermostat or Flue overheat thermostat operated
Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Potterton models that show the neon flashing (Section J/M) fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Potterton neon flashing (Section J/M) 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 7 July 2026