Low
S.24 on Vaillant ecoTEC sustain

Your boiler is working normally and is currently heating up your hot water.

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

DHWmode:Burneron

From this model's manual
Verified against the Vaillant Ecotec Sustain installation & service manual, page 50.
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 is actually not a fault, but a status code indicating that your boiler is currently firing to heat your tap water. It appears when someone turns on a hot tap or if the boiler is pre-heating its internal tank to ensure hot water is ready when you need it. Once the demand for hot water stops, this code will naturally change to a different status.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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