How much does it cost to fix Saunier Duval error code Neon 3 NOT lit?

Typical repair cost for the Saunier Duval Neon 3 NOT lit fault is £150-300 including labour.

Neon 3 NOT lit High

Saunier Duval Neon 3 NOT lit Fault Code

Q: What does the Saunier Duval Neon 3 NOT lit fault code mean?

Your boiler is failing to clear combustion gases properly, so it has safely shut itself down to prevent any risk.

Also written as NEON3NOTLIT — same fault.

The Saunier Duval Neon 3 NOT lit fault code means: your boiler is failing to clear combustion gases properly, so it has safely shut itself down to prevent any risk.. It appears on 2 Saunier Duval models in our database.

Technical description: Air flow proving fault - that is fan or air pressure switch

Typical repair cost £150-300 (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 NOT lit fault code

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

Source

Saunier Duval Neon 3 NOT lit 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