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Error code reference

Jenn-Air Refrigerator Error Code OP

Open thermistor input detected during diagnostic service test.

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Open thermistor input detected during diagnostic service test.

First step from the service manual

Measure thermistor ohms at the specified connector with JP2 removed; if open or short circuit, check thermistor part at terminals in the compartment; if part is good, debug wire harness.

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 Jenn-Air refrigerator

The OP error code on a Jenn-Air refrigerator indicates that an open thermistor input was detected during a diagnostic service test. A thermistor is a temperature-sensitive resistor that the refrigerator's control board uses to monitor compartment temperatures in real time. When the board reads an open circuit from the thermistor circuit, it means the electrical signal it expects from that sensor is absent or outside the valid resistance range, triggering the OP fault code.

The diagnostic process begins by removing connector JP2 and measuring the thermistor's resistance in ohms at the specified connector points. A properly functioning thermistor will return a measurable resistance value within the expected range for the current temperature. If the reading shows an open circuit (infinite or unmeasurably high resistance) or a short circuit (near-zero resistance), the thermistor itself is suspect. The technician should then move to the thermistor terminals directly in the compartment to determine whether the component is at fault or if the wiring is the issue.

If the thermistor reads correctly at its own terminals but the open circuit condition persists at the JP2 connector, the problem lies in the wire harness between the thermistor and the control board. This points to a broken wire, corroded terminal, or a connector that has lost continuity somewhere along its path. Resolving the OP code requires isolating the fault to either the thermistor component itself or the harness, and replacing or repairing whichever element has failed.

Source: manufacturer service documentation.

Common causes of OP

  1. 01

    Failed thermistor

    Part replacement

    The thermistor itself has failed internally, resulting in an open circuit. This is confirmed when resistance measured directly at the thermistor terminals in the compartment reads open or infinite rather than a valid ohm value.

  2. 02

    Broken or damaged wire harness

    Wiring / connection

    A break or disconnection in the wiring between the thermistor and the control board connector JP2 can cause an open circuit reading at the connector even when the thermistor itself is functional. Inspect the full length of the harness for cuts, pinched wires, or loose connectors.

  3. 03

    Corroded or loose connector terminals

    Wiring / connection

    Corrosion or physical looseness at the JP2 connector or the thermistor terminals can interrupt continuity and produce an open circuit reading. Cleaning or reseating the connectors may restore the circuit.

  4. 04

    Disconnected thermistor plug

    Wiring / connection

    The thermistor connector inside the compartment may have come unplugged due to vibration or previous service work. Visually inspect the thermistor connection point to confirm it is fully seated.

See the test procedure for each cause

Frequently asked questions about OP

What does OP mean on a Jenn-Air refrigerator?
The OP code means the refrigerator's control board detected an open circuit from a thermistor input during a diagnostic test. A thermistor is a temperature sensor that provides resistance-based readings to help the refrigerator regulate cooling. The code indicates no valid signal is reaching the board from that sensor circuit. The fault can originate from the thermistor itself or from the wiring that connects it to the control board.
Can I fix the OP error code myself?
Some steps are accessible to knowledgeable DIYers, such as inspecting connector JP2 for loose or corroded terminals and reseating any disconnected plugs. However, accurately diagnosing whether the fault is a failed thermistor or a broken wire harness requires measuring resistance in ohms at specific connector points, which needs a multimeter and some technical familiarity. Replacing the thermistor is a straightforward parts swap if the component is confirmed bad, but tracing and repairing a broken harness can be more involved.
Is it safe to keep using my refrigerator when the OP code is displayed?
It is not advisable to rely on the refrigerator normally while the OP code is active. The faulty thermistor means the control board may not have accurate temperature data for that compartment, which could cause improper cooling or temperature swings. Food safety can be at risk if the refrigerator is not maintaining correct temperatures, so the issue should be diagnosed and repaired promptly.
Will resetting the refrigerator clear the OP error code?
A simple reset by unplugging the refrigerator or cycling the power will not permanently clear the OP code if the underlying fault still exists. The code will return because the control board will continue to detect the open thermistor input once the diagnostic cycle runs again. The error can only be resolved by repairing or replacing the faulty component, whether that is the thermistor or the wire harness.
How much does it cost to repair the OP error code on a Jenn-Air refrigerator?
Repair costs vary depending on the root cause. If only the thermistor needs replacement, parts typically range from around $15 to $60, with a professional labor charge on top of that. If the wire harness requires repair or replacement, costs can be higher, generally ranging from $100 to $300 or more depending on the extent of the damage and local labor rates. Diagnosing the issue first before ordering parts helps avoid unnecessary expense.

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