Low
S.31 on Vaillant ecoFIT Pure 425

Your boiler is perfectly healthy and is simply waiting for a signal from your thermostat to turn on the heating.

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

No heating demand: Summer mode, eBUS controller, waiting period

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 33.
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 your room thermostat or smart controller settingsIncrease the target temperature on your thermostatEnsure the boiler is set to 'Winter' or 'Heating' mode rather than 'Summer' mode

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Related fault codes

S.30View →S.32View →

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