BoilerFaultCodesWhat the manual says
Manufacturer manualOutdoor Unit, Air to Refrigerant Heat Exchanger Outlet Thermistor Error
What causes this fault?
This fault occurs when the sensor monitoring the temperature of the refrigerant as it leaves the heat exchanger stops sending a clear signal. The most common reason is that the thermistor itself has failed or the electrical wiring connecting it to the control board has become loose or damaged. Without this information, the system cannot safely manage the heat exchange process and shuts down to prevent damage.
This fault can be more frequent during periods of heavy vibration or extreme temperature swings, which can stress electrical connections and sensitive sensor components.
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.
Avoid the next call-out bill
A cover plan would handle faults like FC1: no call-out fees, no surprise bills.
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