Low Information
S.23 on Vaillant ecoMAX 618

Your boiler is currently preparing to fire up the burners to heat your water or radiators after a brief pause.

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

Ignition sequence (warm start)

What causes this fault?

This is a normal part of your boiler's operating cycle rather than a mechanical failure. It occurs when the boiler has briefly paused because it reached the desired temperature and is now re-engaging the ignition process to maintain the heat for your home. The 'S' prefix indicates a status message, meaning the system is simply telling you what it is doing at that moment.

DIY fix possible

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

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Related fault codes

S.20View →S.24View →

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