Low
S.3 on Vaillant ecoTEC Regular

Your boiler is currently trying to light the flame to start your central heating.

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

Ignition sequence (heating operation)

From this model's manual
Verified against the Vaillant Ecotec installation & service manual, page 43.
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 normal part of the boiler's operation and occurs every time the system detects a demand for warmth in your radiators. It indicates that the internal fans are spinning and the gas valve is opening to create the spark needed for a flame. You will only see this code during the few seconds it takes for the boiler to successfully ignite.

DIY fix possible

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

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Related fault codes

S. 1View →S. 2View →S. 4View →F.28View →

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