Medium
F.91 on Vaillant ecoFIT Pure 830

Your boiler is having trouble reading the temperature of the water currently stored in your hot water cylinder because there is a faulty sensor or a damaged electrical connection.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

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

Shortcircuit:Cylindertemperaturesensor. NTCsensordefective,shortcircuitinthecableharness,cable/casing

Engineer required

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

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