neon 3 not lit High

Protherm neon 3 not lit Fault Code

Also written as NEON3NOTLIT — same fault.

The Protherm neon 3 not lit fault code means: your boiler has detected an issue with how it moves air and exhaust gases, which has caused it to stop running for safety.. It appears on 1 Protherm 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: Air flow proving fault - that is fan or air pressure switch
Typical repair cost £120-280 (including labour)

Engineer required

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

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Protherm models that show the neon 3 not lit fault code

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

Source

Protherm neon 3 not lit fault code information on this page is sourced and cross-checked against the official Protherm service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026