Low
S.15 on Vaillant ecoTEC sustain

Your boiler is simply performing a routine cooling-down process after you last used hot water, and there is no fault with your system.

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

DHW mode: Pump/fan overrun

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

S.14View →

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