Neon 1 lit (NO) High

Saunier Duval Neon 1 lit (NO) Fault Code

Also written as NEON1LITNO — same fault.

The Saunier Duval Neon 1 lit (NO) fault code means: your boiler is failing to start because it is not receiving a consistent or correctly connected power supply.. 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 and check for correct polarity. Turn the boiler thermostat to its maximum setting. Also check fuses. Correct power supply problem.
Typical repair cost £90-180 (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 1 lit (NO) fault code

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

Source

Saunier Duval Neon 1 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 7 July 2026