High
E35 on Keston Celsius 30

Your boiler has detected an issue with the electrical power timing coming from the mains, which is preventing it from running 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

Mains supply frequency incorrect – may be a problem with the power supply

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

E02View →E34View →E37View →

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