Low
S.O on Vaillant Atmomax

Your boiler is in standby mode because it hasn't received a signal from your thermostat to turn the heating on.

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.

Technical description

Heating issue, no heat demand

DIY fix possible

Check that your room thermostat is turned up higher than the current room temperatureReplace the batteries in your wireless thermostat or programmerEnsure the heating timer or schedule is set to 'On' or 'Auto'

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Related fault codes

S.1View →S.8View →S.31View →

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