Medium
d.27 on Vaillant ecoFIT Pure 835

Your boiler's internal control panel is struggling to communicate with or control an additional accessory or component, such as an external pump or a specific valve.

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 1 (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

F.27View →d.28View →F.70View →

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