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Error code reference

Speed Queen Dryer Error Code OPEN THERMISTOR ERROR

Output board sensed temperature less than 0°F (-18°C) after heater has been active for at least 3 minutes…

Speed Queen codesSpeed Queen dryer codes

Output board sensed temperature less than 0°F (-18°C) after heater has been active for at least 3 minutes, indicating an open thermistor.

First step from the service manual

Press any cycle selection pad after temperature reading rises above 0°F (-18°C) to clear error. Check thermistor and wiring.

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

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What OPEN THERMISTOR ERROR means on a Speed Queen dryer

The OPEN THERMISTOR ERROR on a Speed Queen dryer is triggered when the output board detects a temperature reading below 0°F (-18°C) after the heater has been running continuously for at least 3 minutes. Under normal operation, the thermistor is a temperature-sensitive resistor that sends real-time temperature data to the output board, allowing the control system to regulate heat output. A reading this far below ambient temperature indicates the thermistor circuit is open, meaning the electrical signal has been completely interrupted rather than simply reading low.

An open thermistor condition occurs when the resistance in the sensor circuit becomes effectively infinite, which the control board interprets as an impossibly low temperature. This is distinct from a shorted thermistor, which would cause runaway high readings. The 3-minute delay before the error triggers is intentional, giving the heater sufficient time to produce measurable heat before the board evaluates sensor output. If the temperature signal stays below 0°F (-18°C) through that window, the fault is logged and the error code is displayed.

The most common sources of this fault are a failed thermistor, damaged wiring between the thermistor and the output board, or a loose or corroded connector at either end of that circuit. Physical damage to the thermistor itself, such as from overheating or mechanical contact, can also cause an open condition. Because the error is tied to a real-time sensor reading, it will clear once the board sees a valid temperature above 0°F (-18°C), which makes systematic wiring inspection and thermistor resistance testing the correct starting points for diagnosis.

Source: manufacturer service documentation.

Common causes of OPEN THERMISTOR ERROR

  1. 01

    Failed thermistor

    Part replacement

    The thermistor itself may have an internal break in its resistance element, causing the circuit to read open. Testing the thermistor with a multimeter for resistance continuity will confirm whether the component has failed.

  2. 02

    Broken or damaged wiring

    Wiring / connection

    A wire in the harness between the thermistor and the output board may have broken, chafed through insulation, or shorted to ground. Visually inspect the full wire run and test continuity at both ends.

  3. 03

    Loose or corroded connector

    Wiring / connection

    The connector at the thermistor or at the output board may have pulled partially free or developed corrosion that interrupts the signal. Unplug and reseat connectors, then inspect the terminals for oxidation or bent pins.

  4. 04

    Thermistor physically dislodged from mounting location

    Wiring / connection

    If the thermistor has come loose from its mounting bracket or has shifted away from its intended sensing position, it will not read accurate temperatures and can produce an open-circuit fault. Check that the sensor is properly seated in its housing.

  5. 05

    Output board fault

    Part replacement

    If the thermistor and all wiring check out as good, the output board's sensor input circuit may have failed internally, causing it to misread a valid signal as open. This is the least likely cause and should only be considered after the sensor and wiring are confirmed good.

See the test procedure for each cause

Frequently asked questions about OPEN THERMISTOR ERROR

What does OPEN THERMISTOR ERROR mean on a Speed Queen dryer?
It means the output board detected a temperature reading below 0°F (-18°C) after the heater had been running for at least 3 minutes. That reading indicates the thermistor circuit is completely open, meaning no valid temperature signal is reaching the board. The most likely cause is a failed thermistor or a break in the wiring connecting it to the control board.
Can I reset the OPEN THERMISTOR ERROR without fixing anything?
The error can be cleared by pressing any cycle selection pad once the temperature reading rises above 0°F (-18°C), but if the underlying fault is still present the error will return. Clearing the code without repairing the thermistor or wiring is only useful as a diagnostic step to confirm the fault is active. A permanent fix requires identifying and correcting the open circuit.
Is it safe to keep using my dryer when this error is displayed?
You should not continue running the dryer with this error active. The thermistor is part of the temperature regulation system, and without a working sensor the control board cannot properly monitor or control heat levels. Operating the dryer in this condition could lead to overheating or inadequate drying performance.
How much does it cost to fix an OPEN THERMISTOR ERROR on a Speed Queen dryer?
If only the thermistor needs replacement, parts typically range from $15 to $50 depending on the model, and the repair is relatively straightforward. If the issue turns out to be damaged wiring or a connector, repair costs are mostly labor. An output board replacement, if needed, can range from $100 to $250 or more for parts alone.
How do I test the thermistor on my Speed Queen dryer?
Disconnect power to the dryer before starting any testing. Locate the thermistor, disconnect its wiring harness, and use a multimeter set to measure resistance across the two thermistor terminals. An open reading (infinite resistance, or no continuity) confirms the thermistor has failed and needs replacement. You should also test the wiring harness for continuity from the thermistor connector back to the output board to rule out a broken wire.

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