Low Information
S.17 on Vaillant ecoTEC Pro 28

Your boiler is simply running the pump for a short time after you have used hot water to cool the internal components down safely.

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 overrun. The pump overrun for domestic hot water mode is activated.

What causes this fault?

This is a normal part of your boiler’s operation that happens right after you have finished using a hot tap or the shower. It is triggered because the internal heat exchanger is still very hot, so the pump stays on for a few minutes to move water through the system and dissipate that heat. This protects the internal components from overheating and helps prevent the buildup of limescale.

DIY fix possible

Wait approximately 5 to 10 minutes for the process to finish automaticallyCheck that your hot water taps are fully turned offMonitor the display to see if the code changes to a standby or heating code

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Related fault codes

S.07View →S.10View →S.11View →

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