Neon 3 lit (NO) High

Saunier Duval Neon 3 lit (NO) Fault Code

Also written as NEON3LITNO — same fault.

The Saunier Duval Neon 3 lit (NO) fault code means: your boiler is failing to detect that it is safe to ignite, meaning it has shut down to protect your home and will not provide heating or hot water until repaired.. It appears on 2 Saunier Duval models 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: Isolate electrical supply, check yellow cable between printed circuit board and air pressure switch. If satisfactory replace printed circuit board.
Typical repair cost £180-350 (including labour)

Engineer required

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

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Saunier Duval models that show the Neon 3 lit (NO) fault code

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

Source

Saunier Duval Neon 3 lit (NO) fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026