High
F.23 on Vaillant ecoTEC Plus 826

Your boiler has switched itself off because the water it is heating is not flowing through your pipes fast enough, causing it to overheat in one specific area.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Safetyshutdown:Temper- aturespreadtoogreat

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.22View →F.24View →

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