Neon 3 High

Saunier Duval Neon 3 Fault Code

Also written as NEON3 — same fault.

The Saunier Duval Neon 3 fault code means: your boiler has detected an issue with its internal air supply system, which is preventing it from safely starting up the burner.. 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: Is neon 3 lit? NO: Is there 230V~ between "N/C" on air pressure switch and N? NO: Check yellow cable between printed circuit board and air pressure switch. If satisfactory replace printed circuit board.
Typical repair cost £150-300 (including labour)

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Saunier Duval models that show the Neon 3 fault code

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

Source

Saunier Duval Neon 3 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