High
328 on Worcester Bosch Heatslave

Your boiler is struggling with an unstable electrical supply from the house or the main grid, 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

Internal error with the mains voltage – frequency may be inconsistent

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

203View →235View →FDView →

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