High
F11 on Ferroli Optima 201

Your boiler has stopped working because it cannot correctly read the temperature of the water returning to it, likely due to a loose wire or a faulty sensor.

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 fault (Sensor damaged or wiring shorted / Sensor damaged or wiring broken)

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 →

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