High
F.78 on Vaillant ecoTEC Plus 610

Your boiler is having trouble communicating with the external controls or hot water system, which is preventing it from heating your water correctly.

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

InterruptiontoDHWoutletsensoratexternalcontroller | UKlinkboxisconnected,buthotwaterNTCnotbridged

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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