Medium
231 on Worcester Bosch 24/28/35 CDi MkII

Your boiler has detected a brief loss of electricity or a unstable power supply, causing it to shut down for protection.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

FD Mains power error - electrical power interruption

From this model's manual
Verified against the Worcester Bosch Greenstar Cdi Compact installation & service manual, page 65.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check that the boiler isolation switch and your property's main fuse box (consumer unit) are fully switched on.Unplug the boiler from the wall socket (if applicable) for 30 seconds and plug it back in to perform a soft reset.If the code persists, check for any loose power connections or recent local power cuts in your area.

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