High Lockout
A41 on Ferroli Modena HE

Your boiler has lost communication with the internal sensor that monitors water temperature, meaning it cannot safely heat your home or 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 disconnected

What causes this fault?

This fault occurs when the boiler's main control board loses the electronic signal from the sensor that monitors the temperature of the water leaving the unit. The most common reason is that the sensor itself has developed an internal electrical failure, or the wiring connecting the sensor to the control board has become loose or 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

A06View →F10View →

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