Low
S.109 on Vaillant ecoFIT Pure 412

Your boiler has entered a temporary sleep mode and is currently not running, likely because it is waiting for a signal from your heating controls.

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

Shared across the ecoFIT Pure range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
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 to ensure it is set to call for heatTurn the boiler power supply off at the spur for 30 seconds and switch it back onEnsure your heating programmer is set to 'On' rather than 'Off' or 'Standby'

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Related fault codes

S.108View →S.110View →

All 74 fault codes on the ecoFIT Pure 412

Seeing a different code? Every code this model can display, in one place.

cond.02F.00F.01F.10F.11F.13F.22F.23F.24F.25F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.83F.85F.87F.88F.89P.00P.01P.02P.06S.0S.01S.02S.03S.04S.05S.06S.07S.08S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.34S.39S.42S.46S.53S.54S.88S.91S.96S.98S.99S.108

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