High Lockout
F11 on Ferroli Modena HE

Your boiler's internal sensor that monitors the temperature of the water returning to the unit has stopped communicating correctly, causing the system to shutdown for safety.

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

Return sensor error – t-sensor damaged, short circuited, sensor damaged or wiring broken

What causes this fault?

This fault occurs when the boiler's internal computer loses the ability to read the temperature of the water coming back from your radiators. This is usually caused by the return sensor failing internally due to age or heat stress, or a loose connection in the wiring that prevents the signal from reaching the main control board.

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

F10View →F14View →A06View →

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