High
E15 on Saunier Duval Thelia 23E

Your boiler is struggling to accurately control the internal valve that directs heat to your taps or radiators, meaning it cannot reliably provide hot water or heating.

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

Stepper motor fault

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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