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Error code reference

LG Refrigerator Error Code Ice Room Sensor Error

Sensor system in ICE ROOM has errors; temperature error code displays when sensing temperature is more than…

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Sensor system in ICE ROOM has errors; temperature error code displays when sensing temperature is more than 149°F(+65°C) or less than -58°F(-50°C).

First step from the service manual

Check voltage of MAIN PCB CN31#3 <-> CN76#1: shall be between 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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What Ice Room Sensor Error means on a LG refrigerator

The Ice Room Sensor Error on an LG refrigerator indicates a fault in the temperature sensing system located within the ice maker compartment, also called the ice room. The refrigerator's main PCB continuously monitors the signal from this sensor. When the sensed temperature falls outside the valid operating range, specifically above 149°F (+65°C) or below -58°F (-50°C), the control board flags the reading as invalid and triggers this error code. These threshold values represent the outer limits of what the sensor can physically and accurately measure, so readings beyond these points indicate a sensor failure, a wiring fault, or a loss of voltage supply to the sensor circuit.

The first diagnostic step targets the voltage supply from the main PCB. Measuring across connector CN31 pin 3 and connector CN76 pin 1 should yield a voltage reading between 1.0V and 4.5V. This range corresponds to normal sensor resistance variation across the expected temperature span of the ice room. A reading outside this window, including 0V or 5V, points to either an open circuit, a short to ground, or a failed sensor. The ice room sensor is a thermistor, meaning its resistance changes predictably with temperature. When the thermistor fails open, resistance becomes infinite and the voltage reading climbs to the supply rail. When it fails shorted, resistance drops to near zero and voltage collapses.

Common root causes include a physically damaged sensor, corroded or disconnected wiring at the harness connectors, or a failed main PCB that is not correctly supplying or reading the reference voltage. Ice buildup around the sensor in the ice compartment can also cause erratic readings by mechanically stressing the sensor leads or connector. Technicians should inspect the full wiring path from CN31 to CN76 for pinched wires, moisture intrusion at connectors, and continuity before replacing the sensor itself.

Source: manufacturer service documentation.

Common causes of Ice Room Sensor Error

  1. 01

    Failed Ice Room Thermistor

    Part replacement

    The thermistor sensor itself has failed open or shorted, causing the voltage signal at CN31 pin 3 and CN76 pin 1 to fall outside the 1.0V to 4.5V range. This is the most frequent cause and can be confirmed by measuring sensor resistance directly after disconnecting it from the harness.

  2. 02

    Disconnected or Damaged Wiring Harness

    Wiring / connection

    A loose, corroded, or broken connector at CN31 or CN76 interrupts the signal between the sensor and the main PCB. Visually inspect both connectors and the wiring run through the ice room for pinched, frayed, or moisture-damaged sections.

  3. 03

    Ice Buildup Around the Sensor

    Wiring / connection

    Excessive ice accumulation in the ice room can physically stress the sensor body or its lead wires, causing an intermittent or permanent open circuit. Defrosting the compartment fully and re-checking the voltage reading can confirm whether ice was the cause.

  4. 04

    Short Circuit in the Sensor Circuit

    Wiring / connection

    A short to ground anywhere along the sensor wiring will collapse the voltage to 0V, which falls outside the valid range and triggers the error. This can result from chafed insulation where wires contact a metal edge inside the ice room housing.

  5. 05

    Failed Main PCB

    Part replacement

    If the wiring and thermistor both test correctly but the voltage at CN31 pin 3 and CN76 pin 1 is still out of the 1.0V to 4.5V range, the main PCB may not be supplying the correct reference voltage to the sensor circuit. PCB replacement is a last-resort diagnosis after all other causes are ruled out.

See the test procedure for each cause

Frequently asked questions about Ice Room Sensor Error

What does Ice Room Sensor Error mean on a LG refrigerator?
This error means the temperature sensor located in the ice maker compartment is reporting a value outside the valid range, specifically above 149°F (+65°C) or below -58°F (-50°C). The main PCB interprets these out-of-range readings as a sensor system fault. The underlying cause is usually a failed thermistor, a wiring problem, or a connector issue between the sensor and the control board.
Can I fix the Ice Room Sensor Error myself?
A knowledgeable DIYer can perform several checks, including inspecting the wiring harness connectors at CN31 and CN76 for corrosion or loose connections, defrosting the ice compartment to rule out ice damage, and using a multimeter to verify the voltage reading falls between 1.0V and 4.5V. If the wiring checks out and the sensor tests faulty, replacing the thermistor is a moderately straightforward repair. Main PCB replacement should be left to a qualified technician.
Is it safe to keep using my refrigerator while this error is active?
The refrigerator's main cooling section may continue to operate, but the ice maker could behave erratically or stop producing ice entirely while this error is active. There is no immediate safety hazard to food stored in the main compartment, but you should address the fault promptly to prevent ice maker damage and avoid food spoilage if the error affects overall temperature control.
Will resetting the refrigerator clear the Ice Room Sensor Error?
A power reset by unplugging the unit for a few minutes may temporarily clear the error display, but the code will return if the underlying fault with the sensor or wiring has not been corrected. A reset is useful for confirming whether the error is intermittent, but it is not a repair. The voltage at CN31 pin 3 and CN76 pin 1 must fall within the 1.0V to 4.5V range before the error will clear permanently.
How much does it cost to repair the Ice Room Sensor Error on an LG refrigerator?
If only the thermistor sensor needs replacement, parts typically range from $15 to $60 depending on the specific model, and the repair is relatively inexpensive if done without a service call. If a technician is needed, labor plus parts can bring the total to roughly $100 to $250. Main PCB replacement is the most costly scenario, with parts and labor potentially ranging from $200 to $500 or more.

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