High
d.27 on Vaillant ecoFIT pure

Your boiler's internal control board is having trouble sending a signal to an external component, such as a pump or valve, meaning it cannot operate 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

Function of relay 1 (multi-functional module)

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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Related fault codes

F.27View →d.28View →F.70View →

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