High
F.64 on Vaillant ecoFIT Pure 835

Your boiler's computer is struggling to read internal sensor signals, causing it to shut down to prevent incorrect operation.

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

Electronics/sensor fault

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.63View →F.65View →F.67View →

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