Low
S.91 on Glow-worm Betacom4

Your boiler has been accidentally set to a display-only demonstration mode rather than its normal operating mode.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Maintenance: Demo mode

From this model's manual
Verified against the Glow Worm Betacom4 installation & service manual, page 36.
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

Locate the diagnostic menu on the boiler interface.Look for a setting labeled 'd.91' or 'Demo Mode'.Change the value from '1' to '0' to disable demo mode and save the setting.

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