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Error code reference

Sub-Zero Refrigerator Error Code 06

Refrigerator evaporator thermistor read open or shorted for 10+ seconds, or repeatedly read erratic…

Sub-Zero codesSub-Zero refrigerator codes

Refrigerator evaporator thermistor read open or shorted for 10+ seconds, or repeatedly read erratic temperatures (ICB427R refrigerator section).

First step from the service manual

Check thermistor electrical connections and continuity from thermistor to control board. Check resistance of thermistor for 30,000 to 33,000 ohms at 0°C (32°F).

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
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What 06 means on a Sub-Zero refrigerator

Error code 06 on the Sub-Zero ICB427R refrigerator section indicates a fault with the refrigerator evaporator thermistor. The control board triggers this code when the thermistor signal reads as an open circuit, a short circuit, or produces erratically fluctuating temperature readings for 10 or more consecutive seconds. The evaporator thermistor is a negative temperature coefficient (NTC) resistor that monitors air temperature at the evaporator coil and feeds that data to the control board to regulate compressor and defrost cycles.

The thermistor should read between 30,000 and 33,000 ohms at 0 degrees Celsius (32 degrees Fahrenheit). A reading significantly above this range indicates an open circuit condition, while a reading near zero ohms indicates a short. Erratic resistance fluctuations that fall outside normal parameters can also trigger the fault, even if the thermistor is not fully failed. This type of intermittent behavior often points to a damaged wire harness, corroded connector terminals, or a thermistor that is degrading but has not yet completely failed.

Because the evaporator thermistor directly influences defrost timing and cooling cycle management, a faulty reading can cause the refrigerator section to over-cool, under-cool, or run excessive defrost cycles. Diagnosing this code requires checking the wiring and connectors between the thermistor and the control board, then measuring thermistor resistance directly at the sensor to rule out wiring issues before condemning the thermistor or the board itself.

Source: manufacturer service documentation.

Common causes of 06

  1. 01

    Failed evaporator thermistor

    Part replacement

    The thermistor itself has drifted out of specification or failed completely, producing an open circuit, short, or erratic resistance readings outside the 30,000 to 33,000 ohm range at 0 degrees Celsius. Measure resistance directly at the thermistor terminals to confirm.

  2. 02

    Damaged or corroded wiring harness connector

    Wiring / connection

    Moisture exposure near the evaporator can corrode connector terminals or degrade wire insulation, causing intermittent or lost continuity between the thermistor and the control board. Inspect the connector body and pins closely for oxidation, spread terminals, or moisture intrusion.

  3. 03

    Broken or pinched thermistor wire

    Wiring / connection

    The wiring between the thermistor and the control board may have been pinched, cut, or broken during a previous service or from normal wear, resulting in an open circuit condition. A continuity check from the thermistor connector to the control board input will identify this fault.

  4. 04

    Thermistor probe displaced from mounting position

    Wiring / connection

    If the thermistor probe has shifted out of its designed mounting clip or location at the evaporator, it may read erratic temperatures as it is no longer sensing the correct airflow zone. Verify the probe is properly seated in its bracket near the evaporator coil.

  5. 05

    Control board input fault

    Part replacement

    If the thermistor and all associated wiring test within specification and connections are secure, the thermistor input circuit on the control board may be faulty. This is the least common cause and should only be considered after all wiring and the thermistor have been ruled out.

See the test procedure for each cause

Frequently asked questions about 06

What does 06 mean on a Sub-Zero refrigerator?
Error code 06 indicates that the refrigerator section evaporator thermistor has read as open, shorted, or erratically out of range for 10 or more seconds on the ICB427R model. The thermistor is a resistance-based temperature sensor located at the evaporator coil that the control board uses to manage cooling and defrost cycles. When this sensor fails or loses a reliable connection, the board can no longer accurately regulate the refrigerator compartment temperature.
Can I fix error code 06 on my Sub-Zero refrigerator myself?
A knowledgeable DIYer can check the thermistor wiring connections and measure thermistor resistance with a multimeter, looking for a reading between 30,000 and 33,000 ohms at 0 degrees Celsius. If the connections are secure and the thermistor reads within range, the issue may lie in the wire harness, which can sometimes be repaired. However, if the thermistor or control board needs replacement, comfort with appliance repair and access to the correct parts are required, so a professional technician may be the better choice.
Will resetting my Sub-Zero clear error code 06?
A reset may temporarily clear the code display, but if the underlying fault with the thermistor or its wiring is still present, the code will return once the control board detects the out-of-range condition again for 10 or more seconds. Resetting should only be used after a confirmed repair has been completed to verify that the fault is resolved. Ignoring the code without repair can lead to cooling or defrost performance problems.
Is it safe to keep using my Sub-Zero refrigerator with error code 06 active?
Operating the refrigerator with an active code 06 is not recommended for extended periods, as the control board cannot accurately monitor evaporator temperatures in the refrigerator section. This can result in insufficient cooling, excessive frost buildup, or uncontrolled defrost cycles, all of which may compromise food safety. It is best to address the fault as soon as possible.
How much does it cost to repair error code 06 on a Sub-Zero refrigerator?
If only the evaporator thermistor needs replacement, parts and labor costs typically fall in the range of $150 to $350, depending on your location and service provider. If the wiring harness requires repair or replacement, costs can vary widely based on labor time involved. Control board replacement, if needed, is the most expensive scenario and can range from $400 to $800 or more including labor.

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