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Error code reference

LG Refrigerator Error Code R-sensor open

Refrigerator room temperature sensor open circuit fault

LG codesLG refrigerator codes

Refrigerator room temperature sensor open circuit fault - sensor reading suspected to be below -50°C (above 4.5V at MICOM input).

First step from the service manual

Check R-sensor resistance and wiring; replace sensor if faulty.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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What R-sensor open means on a LG refrigerator

The R-sensor open fault on an LG refrigerator indicates an open circuit condition in the refrigerator compartment temperature sensor. The MICOM (microcomputer control board) monitors the sensor's voltage signal continuously. When that voltage rises above approximately 4.5V at the MICOM input, the control interprets this as a temperature reading below -50°C, which is outside the physically possible operating range. This condition is flagged as an open circuit fault because a broken or disconnected sensor circuit causes the voltage to float high, mimicking an impossibly cold reading.

The R-sensor is a negative temperature coefficient (NTC) thermistor mounted inside the refrigerator compartment. Under normal operation, its resistance decreases as temperature rises, producing a proportional voltage signal the MICOM uses to regulate the compressor and evaporator fan cycling. When the sensor wire breaks, the connector separates, or the thermistor element itself fails internally, the circuit opens and the MICOM loses a valid reference signal. Without accurate compartment temperature data, the refrigerator cannot properly manage cooling cycles, which can lead to temperature instability or continuous compressor operation.

Diagnosis begins with a resistance check of the R-sensor itself and a thorough inspection of the wiring harness from the sensor to the control board. A functioning NTC thermistor should show measurable resistance at room temperature, and that resistance should change predictably with temperature changes. An open circuit reading (infinite or OL resistance) on a multimeter confirms sensor failure. Damaged wiring, corroded connector pins, or a loose connector can also produce this fault without the sensor itself being defective, so harness and connector integrity must be confirmed before condemning the sensor.

Source: manufacturer service documentation.

Common causes of R-sensor open

  1. 01

    Failed R-sensor thermistor

    Part replacement

    The thermistor element inside the sensor has broken internally, creating an open circuit. Confirm this with a multimeter set to resistance: an OL or infinite reading at room temperature indicates a failed sensor that requires replacement.

  2. 02

    Disconnected or loose wiring connector

    Wiring / connection

    The connector joining the sensor harness to the main wiring loom can work loose over time, especially with repeated door vibration. Inspect the connector at both the sensor end and the control board end and reseat any loose connections.

  3. 03

    Broken or damaged wiring harness

    Part replacement

    A wire in the sensor harness can fray, crack, or break due to repeated flexing, pinching during installation, or ice buildup putting stress on the cable. Visually trace the full harness length and use a multimeter to check for continuity.

  4. 04

    Corroded connector pins

    Wiring / connection

    Moisture inside the refrigerator compartment can cause the sensor connector pins to corrode, increasing resistance to the point of an effective open circuit. Check the connector terminals for visible oxidation or greenish deposits and clean or replace as needed.

  5. 05

    Faulty control board input

    Part replacement

    In rare cases, the MICOM or main control board's sensor input circuit can fail, causing it to misread a healthy sensor as open. This should only be considered after confirming the sensor and all wiring test correctly.

See the test procedure for each cause

Frequently asked questions about R-sensor open

What does R-sensor open mean on a LG refrigerator?
The R-sensor open error means the refrigerator compartment temperature sensor has been detected as an open circuit by the control board. The MICOM reads a voltage above 4.5V at its sensor input, which corresponds to a temperature reading below -50°C and is outside any valid operating range. This is most commonly caused by a failed thermistor, a broken wire, or a disconnected connector in the sensor circuit. The refrigerator cannot regulate compartment temperature properly until the fault is resolved.
Can I fix the R-sensor open error myself?
Many homeowners and DIYers can address this fault by inspecting and reseating the sensor wiring connector, which requires no special tools. If the sensor itself has failed, replacing an NTC thermistor is a straightforward repair that involves unplugging the old sensor and plugging in a compatible replacement. A multimeter is helpful for confirming whether the sensor or a wiring issue is the root cause before ordering parts. If the fault points to the main control board, that repair is more complex and may warrant professional service.
Is it safe to keep using my refrigerator while this error is showing?
Continuing to run the refrigerator with this error is not recommended for extended periods. Without a valid temperature signal, the control board cannot accurately cycle the compressor and fans, which may result in the compartment running too warm or too cold. Food safety can be compromised if temperatures are not maintained properly. Address the fault as soon as possible and use a standalone thermometer to monitor compartment temperature in the interim if the refrigerator must stay in use.
How much does it cost to repair the R-sensor open error on an LG refrigerator?
If the repair is limited to reseating a loose connector, there is no parts cost involved. A replacement R-sensor thermistor typically costs in the range of $15 to $50 depending on the specific model. If professional labor is required, expect to add $75 to $200 or more for a service call and diagnostic time. Control board replacement, if needed, is significantly more expensive and can range from $150 to $400 or higher for parts alone.
Will resetting the refrigerator clear the R-sensor open error?
A power reset may temporarily clear the error code from the display, but the fault will return as soon as the control board performs its next sensor check if the underlying problem has not been repaired. Resetting is useful for confirming whether the error is persistent or intermittent, but it is not a fix. The sensor circuit must be inspected and the faulty component corrected to permanently clear the error.

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