BoilerFaultCodesFerroli F12 Fault Code
The Ferroli F12 fault code means: your boiler has lost its connection to the sensor that monitors your hot water temperature, which means you will likely experience cold showers until it is fixed.. It appears on 10 Ferroli models in our database.
Technical description: Domestic hot water (DHW) sensor fault – sensor damaged, wiring shorted or wiring disconnected – check the wiring
What causes the Ferroli F12 fault?
This fault occurs when the boiler's main control board can no longer communicate with the sensor responsible for measuring your hot water temperature. The most common reason is that the internal sensor has developed a technical failure or the electrical wiring connecting it to the system has come loose or become damaged.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Ferroli models that show the F12 fault code
Click a model for the full fault code list and model-specific repair notes.
- Arena 30A Repair: £120-180
- Bluehelix HiTech RRT Repair: £90-160
- Bluehelix Pro RRT Repair: £120-180
- Bluehelix Tech Repair: £90-160
- Bluehelix Tech RRT Repair: £120-220
- Bluehelix Tech RRT 24C Repair: £120-200
- Domiproject Repair: £90-160
- Extrema C Repair: £120-200
- Force W Repair: £120-200
- Modena HE Repair: £90-160
Source
Ferroli F12 fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.
- Ferroli Arena 30A manual (PDF)
- Ferroli Bluehelix HiTech RRT manual (PDF)
- Ferroli Bluehelix Pro RRT manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026