High
Burner reset light orange steady on Worcester Bosch Danesmoor

Your boiler has detected an issue with the electrical power supply coming from the mains, meaning it cannot run safely or consistently.

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.

What the manual says

Manufacturer manual

Frequency supply error — abnormal mains frequency

From this model's manual
Verified against the Worcester Danesmoor Riello 535 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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