Low
S.10 on Vaillant ecoTEC exclusive

Your boiler has detected that you have turned on a hot water tap and is currently working to provide hot water to your home.

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

DHW demand: Domestic hot water requirement via impeller sensor

Shared across the ecoTEC exclusive range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This code appears when the flow sensor inside the boiler detects that water is running through the hot water pipe. It is the boiler's way of confirming that it has successfully registered your request for hot water and is firing up the burner to heat it. This is a normal operational signal rather than a malfunction of any internal components.

DIY fix possible

No action required; this is a status code, not a fault code.Simply turn off your hot water tap to see the code change back to its standby state.

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Related fault codes

All 71 fault codes on the ecoTEC exclusive

Seeing a different code? Every code this model can display, in one place.

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