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Error code reference

U-Line Ice Maker Error Code E1

Thermistor 1 open

U-Line codesU-Line ice maker codes

Thermistor 1 open - Refrigerator Zone thermistor circuit is open.

First step from the service manual

Check thermistor connections and OHM test the thermistor (16.1k ohms at 32°F ice water bath).

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

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What E1 means on a U-Line ice maker

The E1 error code on a U-Line ice maker indicates that the Refrigerator Zone thermistor circuit is open. A thermistor is a temperature-sensing resistor whose resistance changes predictably with temperature. An open circuit condition means the thermistor or its wiring is presenting infinite or unmeasurably high resistance, preventing the control board from receiving any valid temperature signal from the refrigerator zone. Without this input, the unit cannot regulate cooling properly and will halt normal operation to avoid damage.

The thermistor used in the U-Line refrigerator zone is rated at 16.1k ohms when tested in a 32 degree Fahrenheit ice water bath. This spec is the baseline for OHM testing. If a technician submerges the thermistor in an ice water bath and reads significantly higher resistance or an open line (OL) reading on a multimeter, the thermistor itself has failed. If the thermistor tests correctly in isolation, the fault lies in the wiring harness or connector between the sensor and the control board.

Common root causes include connector corrosion, a broken wire in the harness, or outright thermistor failure due to age or moisture exposure. Because the refrigerator zone thermistor directly governs temperature regulation in that compartment, this fault should be addressed promptly. Continued operation without a functioning sensor risks improper ice production, food safety issues, and potential compressor strain from unregulated cycling.

Source: manufacturer service documentation.

Common causes of E1

  1. 01

    Loose or disconnected thermistor connector

    Wiring / connection

    The wiring connector between the thermistor and the control board can loosen over time due to vibration or handling. Inspect the connector at both ends, reseat it firmly, and retest for the error.

  2. 02

    Failed thermistor

    Part replacement

    The thermistor itself may have failed internally, presenting an open circuit. Confirm by OHM testing the sensor in a 32 degree Fahrenheit ice water bath. A reading significantly above 16.1k ohms or an open line (OL) reading confirms the sensor needs replacement.

  3. 03

    Corroded or damaged connector terminals

    Wiring / connection

    Moisture inside the unit can cause corrosion at the thermistor connector pins, increasing resistance to the point of an open circuit condition. Visually inspect the terminals for green or white oxidation and clean or replace the connector as needed.

  4. 04

    Broken or damaged wiring harness

    Part replacement

    A wire in the harness running from the thermistor to the control board may have been pinched, cut, or broken, especially if the unit has been serviced before. Trace the harness along its full length and check for any visible damage or breaks.

  5. 05

    Faulty control board

    Part replacement

    If the thermistor and all wiring check out correctly during testing, the control board input circuit may have failed, causing it to misread a good sensor as an open circuit. This is the least likely cause and should only be considered after all other components are confirmed functional.

See the test procedure for each cause

Frequently asked questions about E1

What does E1 mean on a U-Line ice_maker?
The E1 code on a U-Line ice maker indicates that the Refrigerator Zone thermistor circuit is open, meaning the control board cannot receive a valid temperature reading from that sensor. This is typically caused by a failed thermistor, a disconnected wiring connector, or a break in the wiring harness. The unit cannot regulate the refrigerator zone temperature without this signal, so it halts normal operation until the fault is corrected.
How do I fix the E1 error on my U-Line ice maker?
Start by checking the thermistor wiring connector and reseating it firmly at both the sensor and control board ends. Next, OHM test the thermistor by submerging it in a 32 degree Fahrenheit ice water bath. A properly functioning thermistor should read approximately 16.1k ohms. If the reading is open or far outside that range, replace the thermistor. If the sensor tests correctly, trace the wiring harness for any damage or corrosion.
Will resetting my U-Line ice maker clear the E1 error?
A simple reset will not permanently clear the E1 error if the underlying fault still exists. The code will return as soon as the control board attempts to read the thermistor again. The error will only clear and stay clear after the open circuit condition in the thermistor or its wiring has been diagnosed and repaired.
Is it safe to continue using my U-Line ice maker with an E1 error?
It is not advisable to continue using the unit with an active E1 error. Without a functioning refrigerator zone thermistor, the unit cannot accurately monitor or regulate temperature in that compartment. This can result in improper ice production, inconsistent food safety temperatures if the zone is used for storage, and potential long-term stress on the compressor from unregulated cycling.
How much does it cost to repair a U-Line ice maker E1 error?
If the fix is simply reseating a loose connector, there is no parts cost involved. If the thermistor itself needs replacement, parts typically range from around $20 to $60 depending on the specific model. If a professional technician is needed for diagnosis and repair, expect total costs in the range of $100 to $250 including labor, though this can vary based on your location and service provider.

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