Sub-Zero Refrigerator Error Code 10 F 01

Error code 10 F 01 on a Sub-Zero refrigerator indicates that the freezer evaporator thermistor has been detected in a shorted or closed condition. The evaporator thermistor is a negative temperature coefficient (NTC) resistor positioned near the freezer evaporator coil. Its job is to continuously report coil temperature to the control board, allowing the board to regulate defrost cycles and compressor operation. When the thermistor shorts internally, its resistance collapses to near zero ohms, causing the control board to receive a signal that suggests an impossibly low or erratic temperature reading. This triggers the fault code and may disrupt normal cooling and defrost control.

The thermistor circuit typically operates within a predictable resistance range that corresponds to specific temperatures. A shorted thermistor will read far outside the expected range, usually presenting resistance values well below what the control board considers valid. This failure mode is distinct from an open thermistor fault, where resistance is infinite. A shorted condition can sometimes be caused by moisture intrusion into the sensor body or connector, physical damage to the sensor wire, or internal component degradation over time.

Diagnosing this fault requires disconnecting the thermistor from the wiring harness and measuring its resistance with a multimeter. A shorted sensor will read near 0 ohms rather than the several thousand ohms expected at typical freezer temperatures. Inspect the wiring harness for pinched or chafed insulation that may be causing a short to ground. If the harness checks out, the thermistor itself needs replacement. Reconnecting the sensor after replacement and clearing the fault code should restore normal board communication.