High
Boiler Lock-out on Saunier Duval Semia Condens F30 E

Your boiler has stopped working because it failed to start or stay lit, meaning your heating and hot water will not function.

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

Can be caused by: Insulating gas valves turned off; Ignition electrode dirty or broken; Gas valve faulty; Overheat thermostat faulty or boiler temperature over 100°C; Flue thermostat faulty or in open circuit; Flame polarity reversed; Ionisation electrode dirty or broken; Condensate siphon not draining; or Ignition unit faulty

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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Related fault codes

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