Low Information
S.4 on Vaillant ecoTEC exclusive

Your boiler is operating normally and is currently in the process of heating your home or 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.

Technical description

Status indicator: appliance is running properly in normal operation

What causes this fault?

This is a normal status message indicating that the boiler's burner has successfully ignited and is currently generating heat. It appears when the system is actively responding to a request for central heating or hot water. It is not an error, but rather a confirmation that the combustion process is working exactly as it should.

DIY fix possible

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

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Related fault codes

S.0View →S.1View →S.2View →S.3View →S.7View →S.8View →

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