Viking Refrigerator Error Code Thermistor Alarm

The Viking refrigerator Thermistor Alarm indicates that the control board has detected an open circuit in the thermistor circuit for either the freezer or refrigerator compartment. When this alarm triggers, an audible alarm sounds and the corresponding compartment indicator light activates. Temperature indicators 4 through 7 illuminate in sequence, which is the system's way of communicating that it cannot read a valid temperature signal from the affected thermistor. A thermistor is a temperature-sensitive resistor that changes its resistance value in response to temperature changes, allowing the control board to monitor compartment temperatures in real time. When the circuit reads as open, the control board receives no usable signal.

The most common cause of an open thermistor circuit is a failed thermistor itself. Thermistors can fail due to age, physical damage, or moisture exposure, resulting in a broken internal element that interrupts the circuit entirely. The wiring harness connecting the thermistor to the control board is another frequent culprit, as connectors can corrode, pins can back out, or wires can chafe against cabinet edges over time. In some cases, the control board itself may have a failed input circuit, though this is less common than a sensor or wiring failure.

To begin diagnosing, press the Alarm Off pad to silence the alarm. This does not clear the underlying fault. If the condition is not corrected, the alarm will reset and sound again, confirming the fault is still present. A technician should use a multimeter to check the thermistor's resistance and compare it against the expected resistance curve for the operating temperature. An open reading (infinite resistance) at the thermistor terminals confirms sensor failure. If resistance is normal at the sensor, the wiring harness and connector integrity should be inspected next.