High
E40 on Alpha E-Tec Plus 10 / 18

Your boiler has detected an issue with the electricity supply entering your home, meaning the power frequency is inconsistent and the system has shut down to protect its internal electronics.

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

Mains supply frequency outside limits

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

E41View →E42View →

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