High
Neon 3 lit (NO) on Saunier Duval Xeon 120 FF

Your boiler has stopped working because it cannot confirm that air is flowing correctly through the system to burn fuel safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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