BoilerFaultCodesYour 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.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Domestic hot water (DHW) sensor fault – sensor damaged, wiring shorted or wiring disconnected – check the wiring
What causes this 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.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F12 — no call-out fees, no surprises.
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Ferroli Modena HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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