Medium
d.28 on Vaillant ecoFIT Pure 835

Your boiler is confused about how it should be using its secondary internal electrical switch, which usually controls external equipment like pumps or ventilation.

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

Function of relay 2 (multi-functional module)

Engineer required

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

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Related fault codes

d.27View →F.77View →F.22View →

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