Miele Freezer Error Code F122

F122 is a fault code indicating that the ambient air NTC (Negative Temperature Coefficient thermistor) has failed or is producing readings outside its valid operating range. The ambient air NTC is a temperature sensor that monitors the surrounding air temperature near the freezer unit. NTC thermistors work by changing their electrical resistance in response to temperature changes. The freezer's control board continuously monitors the resistance value from this sensor, and when that value falls outside the expected range, the board interprets it as a faulty sensor rather than a valid temperature reading.

The fault triggers when the resistance value from the ambient air NTC corresponds to a temperature reading below -66°F (-55°C) or above 140°F (60°C). These thresholds represent the outer limits of what the sensor should physically be able to report under any realistic operating condition. A reading outside these bounds almost always points to an electrical fault in the sensor itself or in the wiring connecting it to the control board, rather than an actual extreme ambient temperature condition.

The most direct corrective action is replacing the ambient air NTC. Before replacing the sensor, technicians should inspect the wiring harness and connector pins associated with the NTC circuit for corrosion, breaks, or loose connections, since wiring faults can produce the same out-of-range resistance readings as a failed sensor. If the wiring checks out, the sensor itself is the likely failed component and should be replaced.