Low
S.03 on Vaillant ecoTEC plus aquaPLUS

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 Plus Aquaplus installation & service manual, page 38.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check if your thermostat is calling for heatWait a few minutes to see if the boiler transitions to a run codeEnsure your gas supply is turned on if the boiler fails to light

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S.01View →S.02View →F.28View →F.29View →

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