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Error code reference

LG Refrigerator Error Code EXT-SENSOR

External/ambient temperature sensor error

LG codesLG refrigerator codes

External/ambient temperature sensor error: electric wire cut, short-circuit, contact failure, or sensor housing missing; displayed when sensor temperature is not lower than 122°F nor higher than -58°F.

First step from the service manual

Check the voltage between Main PCB CN 10 No. 8 ↔ 7 to see if it is between 4.5V and 1.0V.

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

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What EXT-SENSOR means on a LG refrigerator

The EXT-SENSOR error code on an LG refrigerator indicates a fault in the external or ambient temperature sensor circuit. This sensor monitors the surrounding environment outside the refrigerator cabinet and feeds that data to the main PCB so the control system can adjust compressor and fan operation accordingly. The error triggers when the sensor reports a temperature reading that falls outside the valid operating range, specifically when the reading is not lower than 122°F (the upper limit) and not higher than -58°F (the lower limit). Any reading outside this window is interpreted by the control board as a sensor failure rather than an actual ambient condition.

The fault can originate from several points in the sensor circuit. The most common culprits are an open wire (cut or broken conductor), a short-circuit in the sensor wiring harness, a poor or corroded connector contact, or a physically missing sensor housing. Each of these conditions disrupts the resistance-to-voltage relationship that the main PCB uses to interpret temperature. The control board monitors this circuit through connector CN 10, specifically between pins 8 and 7. Under normal operating conditions, the voltage at this connector should measure between 1.0V and 4.5V. A reading outside this range confirms a wiring or sensor fault.

Diagnosing this code requires a multimeter and access to the main PCB connector. Start by measuring voltage at CN 10 pins 8 and 7. If the voltage is out of range, inspect the wiring harness for breaks, pinched sections, or damaged insulation. Check each connector contact for corrosion or looseness. If wiring checks out, the sensor itself may have failed and requires replacement.

Source: manufacturer service documentation.

Common causes of EXT-SENSOR

  1. 01

    Open or broken wire in sensor circuit

    Wiring / connection

    A cut or broken conductor in the wiring harness between the external sensor and the main PCB will prevent any valid voltage signal from reaching CN 10 pins 8 and 7. Inspect the full length of the harness for visible damage, kinks, or breaks.

  2. 02

    Failed external temperature sensor

    Part replacement

    The sensor itself can fail internally, causing it to report a resistance value that falls outside the valid temperature range. If wiring and connectors check out, the sensor is the likely component to replace.

  3. 03

    Loose or corroded connector contact

    Wiring / connection

    Poor contact at any connector in the sensor circuit can cause intermittent or out-of-range voltage readings at CN 10. Check each connector for corrosion, bent pins, or incomplete seating.

  4. 04

    Short-circuit in sensor wiring

    Wiring / connection

    A wiring harness that has been pinched, chafed against a sharp edge, or exposed to moisture can develop a short-circuit. This will pull the voltage reading at CN 10 outside the 1.0V to 4.5V normal range.

  5. 05

    Missing or improperly installed sensor housing

    Part replacement

    If the sensor housing is absent or dislodged, the sensor element may be exposed or disconnected, causing the circuit to read an invalid temperature. Confirm the sensor housing is present and properly secured at its mounting location.

See the test procedure for each cause

Frequently asked questions about EXT-SENSOR

What does EXT-SENSOR mean on a LG refrigerator?
EXT-SENSOR indicates a fault in the external or ambient temperature sensor circuit. The error appears when the sensor reports a temperature outside the valid range of -58°F to 122°F, which tells the control board the circuit is not functioning correctly. Possible causes include a broken wire, short-circuit, bad connector contact, or a missing sensor housing.
Can I fix the EXT-SENSOR error myself?
Some causes of this error are DIY-friendly. Start by unplugging the refrigerator and visually inspecting the sensor wiring harness and connectors for obvious damage or loose connections. If you have a multimeter, check the voltage at main PCB connector CN 10 between pins 8 and 7 to see if it falls within the 1.0V to 4.5V normal range. If the wiring is intact and the sensor itself has failed, replacing the sensor is a moderate-difficulty repair that many experienced DIYers can complete.
Will resetting my LG refrigerator clear the EXT-SENSOR error?
A power reset may temporarily clear the error code from the display, but it will return if the underlying sensor circuit fault is not repaired. The main PCB continuously monitors the sensor voltage at CN 10, so any persistent wiring issue, short, or failed sensor will trigger the code again after the reset.
Is it safe to keep using my refrigerator with the EXT-SENSOR error showing?
The refrigerator may continue to run with this error active, but its ability to optimize cooling based on room conditions will be compromised. For short periods this is generally not dangerous, but prolonged operation without a functioning ambient sensor can reduce efficiency and potentially affect cooling performance. It is best to diagnose and repair the fault promptly to avoid food safety concerns.
How much does it cost to repair the EXT-SENSOR error on an LG refrigerator?
Repair costs depend on the root cause. If only a wiring repair or connector reseating is needed, the cost may be minimal, primarily your time or a small labor charge. If the external temperature sensor itself needs replacement, parts typically range from $15 to $50 depending on the specific model. If the main PCB is involved, costs can rise to $150 to $400 or more including parts and professional labor.

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