Low
S.31 on Vaillant ecoTEC pro 30 H combi A VUW GB 306/5-3

Your boiler is simply set to summer mode, which means the central heating is turned off while hot water continues to work normally.

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

Summer mode is activated; there is no heat demand.

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Pro Ecotec Plus Combi installation & service 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 boiler control panel or external room thermostat.Switch the operating mode from summer mode (often indicated by a sun icon or hot water only) to winter/heating mode.Increase the target room temperature above the current room temperature to trigger a heat demand.

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Related fault codes

S.30View →S.00View →S.04View →

All 82 fault codes on the ecoTEC pro 30 H combi A VUW GB 306/5-3

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

F.00F.01F.10F.11F.20F.22F.23F.24F.25F.26F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.77F.78F.83F.84F.85S.00S.01S.02S.03S.04S.05S.06S.07S.08S.10S.11S.13S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.32S.34S.39S.40S.41S.42S.46S.53S.54S.57S.58S.61S.62S.63S.76S.88S.92S.93S.96S.97S.98S.99

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