Low
S.34 on Vaillant ecoTEC pro 30 H combi A VUW GB 306/5-3

Your boiler has automatically activated its built-in frost protection mode because the internal temperature has dropped too low.

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

The frost protection function for heating mode is activated.

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

Wait for the boiler to complete its frost protection cycle once internal temperatures rise.Ensure your heating controls and thermostat are switched on so the boiler can maintain a safe background temperature.Check that your property is adequately heated and internal pipes are not at risk of freezing during severe cold weather.

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Related fault codes

S.30View →S.31View →F.75View →

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.31S.32S.39S.40S.41S.42S.46S.53S.54S.57S.58S.61S.62S.63S.76S.88S.92S.93S.96S.97S.98S.99

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