Medium
12 on Alpha FMK

Your boiler is struggling to read the temperature of the water in your cylinder, which means your hot water system may not function correctly.

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

Cylinder sensor fault (FlowSmart only)

Engineer required

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

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