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Error code reference

Whirlpool Freezer Error Code OP

Open circuit detected on the thermistor (resistance greater than 88k ohms).

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Open circuit detected on the thermistor (resistance greater than 88k ohms).

First step from the service manual

Check wires and connectors. Disconnect power or unplug product. Check resistance given in the diagram.

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

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What OP means on a Whirlpool freezer

The OP error code on a Whirlpool freezer indicates an open circuit condition on the thermistor, meaning the control board is reading a resistance value greater than 88k ohms from the temperature sensor circuit. A properly functioning thermistor changes its resistance in response to temperature, and the control board uses these readings to regulate the compressor and maintain the correct freezer temperature. When resistance climbs above the 88k ohm threshold, the board interprets this as a broken or disconnected circuit rather than a valid temperature reading, and the OP code is triggered.

The thermistor itself is a negative temperature coefficient (NTC) sensor, meaning its resistance decreases as temperature rises. An open circuit fault typically points to a complete break in the sensor loop, which can occur at the thermistor itself, at a wiring connector, or anywhere along the wiring harness between the sensor and the control board. Because the board can no longer determine actual cabinet temperature, the freezer may not cool correctly or may default to a safe operating mode.

The first diagnostic step is to inspect all wiring and connectors in the thermistor circuit before replacing any parts. Disconnect power to the unit, then use a multimeter to measure the resistance across the thermistor and compare it against the resistance values shown in the wiring diagram for that model. A reading above 88k ohms or an infinite reading (OL) confirms an open circuit. This test helps determine whether the fault is in the sensor itself or in the wiring and connectors connecting it to the board.

Source: manufacturer service documentation.

Common causes of OP

  1. 01

    Faulty thermistor (temperature sensor)

    Part replacement

    The thermistor itself may have failed internally, causing its resistance to exceed 88k ohms or go completely open. Confirm this by measuring resistance across the thermistor terminals with a multimeter and comparing to the diagram values.

  2. 02

    Loose or disconnected wiring connector

    Wiring / connection

    Connectors in the thermistor circuit can loosen over time due to vibration or frost buildup. Inspect each connector in the thermistor wiring path and reseat any that appear loose or corroded.

  3. 03

    Damaged wiring harness

    Part replacement

    The wire between the thermistor and the control board may be pinched, broken, or chafed, creating an open circuit. Visually trace the harness and use a multimeter to check continuity along each wire.

  4. 04

    Corroded connector terminals

    Wiring / connection

    Moisture inside the freezer cabinet can cause corrosion at connector terminals, increasing resistance or breaking the circuit entirely. Look for green or white oxidation on metal terminals and clean or replace affected connectors.

  5. 05

    Failed control board

    Part replacement

    If the thermistor and all wiring test within normal resistance values, the control board's sensor input circuit may have failed and could be misreading the signal. The control board should be considered only after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about OP

What does OP mean on a Whirlpool freezer?
The OP code means the freezer's control board has detected an open circuit on the thermistor, with resistance measuring above 88k ohms. The thermistor is the temperature sensor the freezer uses to monitor and regulate its internal temperature. When the circuit is open, the board cannot get a valid reading and triggers the OP alert. This can be caused by a failed sensor, a broken wire, or a loose connector.
Can I fix the OP error code myself?
Some causes of the OP code are DIY-friendly, particularly reconnecting a loose or unplugged wiring connector. Start by disconnecting power to the freezer, then inspect the thermistor wiring and connectors for any obvious damage or disconnection. Testing the thermistor resistance with a multimeter and comparing it to the diagram values will confirm whether the sensor needs replacing. If the wiring and sensor both test good, diagnosing the control board typically requires professional service.
Is it safe to keep using my freezer while the OP code is displayed?
It is not recommended to continue using the freezer normally with an active OP error. Because the control board cannot read the cabinet temperature accurately, the freezer may not maintain safe storage temperatures for food. The compressor could run erratically or not at all, putting frozen food at risk. Address the error as soon as possible to avoid food spoilage.
How much does it cost to repair the OP error on a Whirlpool freezer?
Repair costs depend on which component has failed. A replacement thermistor is typically the least expensive fix, with parts generally ranging from $15 to $50 and professional labor adding $75 to $150 or more. If the control board is at fault, parts alone can range from $100 to $250 or higher, plus labor. Getting a diagnostic visit from a technician will give you a more accurate estimate for your specific model.
Will resetting the freezer clear the OP error code?
Unplugging the freezer or cycling power may temporarily clear the OP code display, but the error will return if the underlying fault is still present. The thermistor circuit must be repaired or the failed component replaced before the code will clear permanently. Resetting without fixing the root cause does not restore accurate temperature monitoring and is not a solution.

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