High
F6 on Saunier Duval Semia Condens F30 E

Your boiler has stopped working because it is unable to accurately measure the temperature of the water circulating through your heating system.

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

Central heating flow thermistor fault. Thermistor cable defective/broken. Thermistor faulty. Check that thermistor attached correctly to pipe

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

F7View →

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