Low
S.109 on Vaillant ecoFIT Pure 435

Your boiler has entered a temporary standby mode, which is a normal state and not a fault, usually indicating it is waiting for a command from your heating controls or timer.

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

Product's standby mode activated

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 programmer to ensure a heating or hot water demand is activeTurn the heating setpoint on the boiler up to see if it respondsWait a few minutes to see if the boiler cycles back into operation automatically

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