Medium
F.78 on Vaillant ecoFIT Pure 418

Your boiler has lost the connection to the temperature sensor that controls your hot water, meaning it cannot properly heat the water for your taps.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Interruption to DHW outlet sensor at external controller

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.73View →F.74View →

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