BoilerFaultCodesTechnical description
Central Heating flow thermistor disconnected (frost protection).
What causes this fault?
This fault occurs when the boiler's control board loses communication with the temperature sensor on the main heating pipe. The most common reason is that the sensor has developed an internal electrical failure or the wiring connecting it to the brain of the boiler has become loose or damaged.
This fault is frequently triggered during the first cold snap of autumn when the system's frost protection kicks in and attempts to read a sensor that has degraded over the summer.
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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