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Error code reference

LG Refrigerator Error Code R1 sensor

Refrigerator sensor (1) abnormal

LG codesLG refrigerator codes

Refrigerator sensor (1) abnormal - short circuit or open circuit in the primary refrigerator temperature sensor.

First step from the service manual

Check for loose connection at CON7, then unplug connector and measure resistance between white wires.

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

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What R1 sensor means on a LG refrigerator

The R1 sensor error on an LG refrigerator indicates an abnormal signal from the primary refrigerator compartment temperature sensor. This sensor is a negative temperature coefficient (NTC) thermistor, meaning its electrical resistance changes predictably as temperature changes. The control board monitors this resistance continuously to determine the internal temperature of the refrigerator compartment. When the board detects a reading that falls outside the expected resistance range, it logs the R1 fault and may alter or disable normal cooling operation to prevent further issues.

The fault is triggered by one of two electrical conditions: a short circuit, where resistance drops far below the expected range, or an open circuit, where the circuit is broken and resistance reads extremely high or infinite. Either condition makes it impossible for the control board to get an accurate temperature reading. The primary connector to inspect is CON7, which carries the sensor signal wires. With the connector unplugged, resistance should be measured directly across the white wires of the sensor harness. A reading that is near zero ohms suggests a short, while an infinite or open reading points to a broken wire or failed sensor.

Common causes include connector corrosion or looseness at CON7, physical damage to the sensor wiring harness, moisture intrusion into the connector, or an outright thermistor failure. Because the sensor is part of the refrigerator compartment temperature management system, an unresolved R1 fault can result in the fridge running too cold, not cold enough, or cycling erratically. Addressing the wiring connections before replacing the sensor is the recommended first step, as loose or corroded connectors at CON7 are a frequent root cause.

Source: manufacturer service documentation.

Common causes of R1 sensor

  1. 01

    Loose or corroded connector at CON7

    Wiring / connection

    The CON7 connector can work loose over time or develop corrosion that interrupts the sensor signal. This is the first thing to inspect, as reseating or cleaning the connector sometimes resolves the error without any parts replacement.

  2. 02

    Failed NTC thermistor (R1 sensor)

    Part replacement

    The thermistor itself can fail, producing either a short circuit or open circuit reading when measured across the white wires. If resistance reads near zero or shows no continuity after confirming good wiring, the sensor requires replacement.

  3. 03

    Damaged or broken sensor wiring harness

    Part replacement

    Physical damage, pinching, or rodent activity can break or short the wires between CON7 and the sensor. Inspect the harness along its entire length for visible cuts, kinks, or bare wire contact points.

  4. 04

    Moisture intrusion into the connector

    Wiring / connection

    Condensation or a water leak inside the refrigerator compartment can allow moisture into the CON7 connector, causing a short circuit condition. Look for water staining or corrosion on the connector terminals.

  5. 05

    Faulty main control board

    Part replacement

    If the sensor and all wiring test within normal resistance values and the connector is secure, the control board itself may be misreading the sensor signal. This is the least likely cause and should only be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about R1 sensor

What does R1 sensor mean on a LG refrigerator?
The R1 sensor error indicates that the primary refrigerator compartment temperature sensor is showing an abnormal reading, specifically a short circuit or open circuit condition. The control board cannot get a valid temperature signal from this sensor, which can disrupt normal cooling. The sensor is a thermistor located in the refrigerator compartment, and the fault is detected through its connector at CON7.
Can I fix the R1 sensor error myself?
A knowledgeable DIYer can often resolve this error by locating the CON7 connector, checking that it is fully seated, and inspecting the white sensor wires for visible damage. If the connector is secure, you can unplug it and use a multimeter to measure resistance across the white wires to determine whether the thermistor has failed. Replacing a thermistor is a straightforward repair, though working with the refrigerator's internal wiring does require some comfort with basic electrical testing.
Is it safe to keep using my refrigerator while the R1 sensor error is active?
With the R1 fault active, the refrigerator may not maintain accurate temperatures in the fresh food compartment, which creates a food safety risk over time. Short-term use while arranging a repair is generally acceptable, but you should monitor the compartment temperature with a separate thermometer and avoid storing perishables if the fridge is not cooling consistently.
How much does it cost to fix the R1 sensor error on an LG refrigerator?
If only the thermistor needs replacement, parts typically cost in the range of $15 to $50 depending on the specific model. Professional labor to diagnose and replace the sensor can add $100 to $200 to the total. If the issue is simply a loose connector at CON7, there may be no parts cost at all.
Will resetting my LG refrigerator clear the R1 sensor error?
A power reset may temporarily clear the error code from the display, but the fault will return if the underlying problem with the sensor or wiring has not been corrected. The control board will detect the abnormal resistance again during its next monitoring cycle and re-trigger the R1 code. A reset is useful for confirming whether a connection issue was resolved, but it is not a substitute for diagnosing and repairing the root cause.

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