Low
S.01 on Vaillant ecoTEC plus Regular

Your boiler is performing a normal startup procedure by clearing out the combustion chamber before it begins heating your home.

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

Heatingmode:Advancefanoperation

From this model's manual
Verified against the Vaillant Ecotec Plus Regular installation & service manual, page 32.
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 a brief preparatory phase where the boiler's fan spins up to push air through the system and clear any leftover gases from the burner area. It is a necessary safety check to ensure the chamber is fresh and ready for a clean ignition. This is not a malfunction, but rather a standard step in the sequence before the heating starts.

DIY fix possible

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

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Related fault codes

S.02View →S.04View →

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