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Error code reference

LG Refrigerator Error Code ICE MAKER SENSOR ERROR

Ice maker sensor fault

LG codesLG refrigerator codes

Ice maker sensor fault — sensor housing slip-out, contact defect, wire cut, wire short, or sensor temperature out of range.

First step from the service manual

Check voltage between Main PCB CN90 pins 3↔4; it shall be within 4.5V~1.0V.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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What ICE MAKER SENSOR ERROR means on a LG refrigerator

The ICE MAKER SENSOR ERROR on an LG refrigerator indicates a fault in the ice maker's temperature sensor circuit. This sensor is a thermistor that monitors the temperature within the ice maker assembly, allowing the control system to regulate the ice-making cycle. The Main PCB communicates with this sensor through connector CN90, and the diagnostic specification calls for a voltage reading between pins 3 and 4 that falls within the 4.5V to 1.0V range. A reading outside this window tells the board that the sensor signal is not valid.

The fault can originate from several points along the sensor circuit. Physically, the sensor housing may have slipped out of its mounting position, breaking consistent contact with the surface it is meant to measure. The electrical connection at the sensor plug can suffer from contact defects such as corrosion or bent terminals. The wiring harness between the sensor and the Main PCB may have a cut or break in one or more conductors, or a short circuit where wires contact each other or a grounded surface. Finally, even if the wiring and connections are intact, the thermistor itself can fail and report a temperature value that falls outside the acceptable operating range for the ice maker.

Diagnosis should begin at Main PCB connector CN90 by measuring DC voltage between pins 3 and 4 with the refrigerator powered on. A voltage outside the 4.5V to 1.0V specification confirms the fault is present in that circuit at that moment. From there, inspect the sensor housing for proper seating, check the harness for visible damage, and test the thermistor resistance directly to isolate whether the fault lies in the wiring or the sensor component itself.

Source: manufacturer service documentation.

Common causes of ICE MAKER SENSOR ERROR

  1. 01

    Sensor housing slipped out of position

    Wiring / connection

    The thermistor housing can work loose from its mounting clip over time, losing firm contact with the surface it measures and producing an erratic or out-of-range signal. Visually inspect the sensor mounting location in the ice maker compartment to confirm the housing is fully seated.

  2. 02

    Wiring harness damage (cut or short)

    Part replacement

    The wire running from the ice maker sensor to Main PCB connector CN90 can be pinched, cut, or shorted against a metal surface, interrupting or distorting the voltage signal. Carefully inspect the full length of the harness for visible breaks, abrasion, or contact with sharp edges.

  3. 03

    Connector contact defect at sensor plug

    Wiring / connection

    Corrosion, bent terminals, or a loose plug at the sensor connector can create high resistance in the circuit, pushing the CN90 pin 3 to 4 voltage outside the 4.5V to 1.0V specification. Unplug and re-seat the connector, then inspect the terminals for damage or oxidation.

  4. 04

    Failed ice maker thermistor

    Part replacement

    The thermistor element itself can fail open or short internally, causing the resistance and corresponding voltage at CN90 to fall outside the valid range even when all wiring is intact. Testing the thermistor resistance directly and comparing it against the expected value for the current temperature will confirm this failure.

  5. 05

    Main PCB fault at CN90

    Part replacement

    If the sensor, wiring, and connector all test correctly, the CN90 circuit on the Main PCB may have a component-level failure preventing it from reading or supplying the correct reference voltage. This is the least common cause and should only be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about ICE MAKER SENSOR ERROR

What does ICE MAKER SENSOR ERROR mean on a LG refrigerator?
This error means the refrigerator's control board has detected a problem with the temperature sensor in the ice maker. The sensor circuit, monitored through Main PCB connector CN90 pins 3 and 4, is producing a voltage outside the expected 4.5V to 1.0V range. The cause can be a dislodged sensor housing, damaged wiring, a faulty connector, or a defective thermistor. Ice production will typically stop until the fault is corrected.
Can I fix the ICE MAKER SENSOR ERROR myself on my LG refrigerator?
Some causes are accessible to a knowledgeable DIYer. Re-seating a slipped sensor housing or re-connecting a loose plug requires no special tools and no replacement parts. Testing voltage at CN90 pins 3 and 4 requires a multimeter and comfort working around live appliance circuits. Replacing a wiring harness or thermistor is a moderate repair that most DIYers with basic electrical skills can complete, though Main PCB replacement is typically better left to a technician.
Is it safe to use my LG refrigerator when the ICE MAKER SENSOR ERROR is displayed?
The error affects only the ice maker circuit and does not directly impact the refrigerator or freezer cooling sections. Food storage should remain safe as long as the refrigerator and freezer compartments are maintaining proper temperatures. However, the ice maker will likely be disabled, so you should not expect ice production until the fault is resolved.
How much does it cost to repair the ICE MAKER SENSOR ERROR on an LG refrigerator?
Repair cost depends heavily on the root cause. A simple re-seat of the sensor housing costs nothing. Replacing the ice maker thermistor typically runs between $20 and $60 for the part, plus labor if a technician is involved. A wiring harness repair or replacement may cost $30 to $100 in parts. Main PCB replacement, if required, is the most expensive outcome, generally ranging from $150 to $400 or more depending on the model, not including labor charges.
Will resetting my LG refrigerator clear the ICE MAKER SENSOR ERROR?
A power reset may temporarily clear the error code, but the fault will return if the underlying problem with the sensor circuit has not been fixed. Resetting is useful for confirming whether the issue is intermittent or persistent, but it is not a repair. If the code reappears after the refrigerator restarts, the sensor, wiring, or connector must be inspected and corrected before the error will stay clear.

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