High
A42 on Ferroli iBoiler 28

Your boiler has detected a problem with the internal sensor that monitors water temperature moving through the system, meaning it cannot safely manage your heating or hot water.

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

Flow sensor error – sensor damaged

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

A03View →F10View →

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