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Error code reference

Viking Refrigerator Error Code Open Thermistor

Either the freezer or refrigerator thermistor circuit has opened, causing alarm sounds and temperature…

Viking codesViking refrigerator codes

Either the freezer or refrigerator thermistor circuit has opened, causing alarm sounds and temperature indicators 4 through 7 to turn on in sequence.

First step from the service manual

Press Alarm Off pad to turn off alarm; alarm will retest for normal operation and sound again if condition has not been corrected.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What Open Thermistor means on a Viking refrigerator

The Open Thermistor error on a Viking refrigerator indicates that the electrical circuit connected to either the freezer thermistor or the refrigerator compartment thermistor has broken open, meaning continuity in that circuit has been lost. Thermistors are temperature-sensing resistors that feed real-time temperature data to the control board. When the circuit opens, the control board can no longer receive valid temperature readings, triggering the alarm system and illuminating temperature indicators 4 through 7 in sequence as a visual alert.

This type of fault differs from a short circuit condition. An open circuit means the signal has been completely interrupted rather than producing an out-of-range reading. The most common causes include a failed thermistor with an internally broken resistive element, a wiring harness with a broken conductor or disconnected connector, or corrosion at a terminal that has severed the electrical path. Physical damage to the sensor wire from ice buildup or mechanical contact can also cause the circuit to open.

Because the control board is receiving no temperature signal, it cannot confirm whether the refrigerator or freezer is maintaining safe food storage temperatures. The system responds by sounding the alarm to prompt immediate attention. Pressing the Alarm Off pad silences the alert temporarily and initiates a retest cycle. If the open circuit condition persists, the alarm will sound again, confirming the fault has not been resolved and that further diagnosis is required.

Source: manufacturer service documentation.

Common causes of Open Thermistor

  1. 01

    Failed thermistor

    Part replacement

    The thermistor itself may have developed an internal break in its resistive element, completely severing the signal circuit. Testing the thermistor with a multimeter for continuity or expected resistance values will confirm whether the component has failed.

  2. 02

    Broken or disconnected wiring harness

    Wiring / connection

    The wire harness leading from the thermistor to the control board may have a broken conductor, a pulled connector, or a crimped section that has fractured. Inspecting the harness along its full length and checking connector seating is an essential early diagnostic step.

  3. 03

    Corroded or loose terminal connection

    Wiring / connection

    Moisture inside the refrigerator or freezer compartment can cause terminal pins at the thermistor connector to corrode, increasing resistance until the circuit effectively opens. Cleaning or replacing the affected connector may restore the circuit.

  4. 04

    Thermistor damaged by ice buildup

    Part replacement

    Excessive frost accumulation around the thermistor can physically stress or fracture the sensor wire or the sensor body itself, especially in the freezer compartment. Defrosting the unit and inspecting the sensor location can reveal this type of damage.

  5. 05

    Control board fault

    Part replacement

    If the thermistor and all associated wiring test within normal parameters, the control board's thermistor input circuit may have failed, causing it to read the circuit as open even when it is intact. This is less common and is typically diagnosed after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about Open Thermistor

What does Open Thermistor mean on a Viking refrigerator?
The Open Thermistor error means the electrical circuit connected to either the freezer or refrigerator temperature sensor has lost continuity, so the control board cannot receive a valid temperature reading. The alarm sounds and temperature indicators 4 through 7 illuminate in sequence to alert you to the condition. The fault must be diagnosed and repaired because the unit cannot confirm proper cooling is occurring while the circuit remains open.
Will pressing the Alarm Off pad fix the Open Thermistor error on my Viking refrigerator?
Pressing the Alarm Off pad will silence the alarm temporarily, but it does not repair the underlying fault. The control system will retest the thermistor circuit automatically, and the alarm will sound again if the open circuit condition has not been corrected. The Alarm Off pad is a diagnostic aid, not a reset that clears the error permanently.
Is it safe to keep food in my Viking refrigerator while the Open Thermistor error is active?
Because the control board cannot confirm actual compartment temperatures when this error is present, there is no reliable way to know whether food is being maintained at safe storage temperatures. Food safety guidelines recommend discarding perishables if proper temperature cannot be verified. It is best to address the fault promptly or transfer food to an alternative refrigerator until the repair is complete.
How much does it cost to repair an Open Thermistor error on a Viking refrigerator?
Repair costs depend on which component has failed. A replacement thermistor sensor typically costs in the range of $15 to $60 for the part, while professional labor to diagnose and install it can add $100 to $250 or more depending on your location. If the control board is the root cause, part costs can rise significantly, generally falling in the $200 to $500 range or higher for that component alone.
Can I diagnose the Open Thermistor error myself, or do I need a technician?
A knowledgeable DIYer with a multimeter can perform basic diagnostics, including checking the thermistor for continuity and inspecting the wiring harness for visible breaks or loose connectors. However, accessing the thermistor and control board connections in some Viking models requires disassembly of interior panels, and interpreting resistance values correctly requires some technical background. If you are not comfortable with electrical diagnostics, a qualified appliance technician is the safer option.

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