BoilerFaultCodesIdeal FC1 Fault Code
The Ideal FC1 fault code means: your heat pump's outdoor sensor that monitors temperature change is not reporting correctly, which prevents the system from managing heat exchange properly.. It appears on 1 Ideal model in our database.
Technical description: Outdoor Unit, Air to Refrigerant Heat Exchanger Outlet Thermistor Error
What causes the Ideal FC1 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the FC1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal FC1 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026