Low
S.34 on Vaillant ecoTEC plus aquaPLUS

Your boiler has detected very cold temperatures and has automatically turned on its built-in safety mode to prevent the internal pipes from freezing.

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

Frost protection mode

From this model's manual
Verified against the Vaillant Ecotec Plus Aquaplus installation & service manual, page 38.
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

Ensure your main heating controls or thermostat are turned up slightly to help warm the systemCheck that any radiator valves in cold rooms are openEnsure there is power to the boiler so the pump can circulate the warm water

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