Low Information
S.01 on Vaillant ecoTEC Plus 938

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.

Technical description

Heatingmode:Advancefanoperation

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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