Medium
F.86 on Vaillant ecoFIT Pure 412

Your boiler has detected that the external sensor or switch connected to your underfloor heating system is not sending a proper signal.

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

Underfloor heating contact fault

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.83View →F.84View →

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