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Error code reference

LG Refrigerator Error Code 05

Ambient air sensor error

LG codesLG refrigerator codes

Ambient air sensor error - connector missing, contact failure, wire cut, short circuit, or sensor failure.

First step from the service manual

Check voltage between MAIN PCB CN40 #1 (YELLOW) and #2 (YELLOW); should 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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  • 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 05 means on a LG refrigerator

Error code 05 on an LG refrigerator indicates a fault in the ambient air temperature sensor circuit. This sensor monitors the temperature of the air surrounding the refrigerator and feeds that data back to the main PCB so the control board can make accurate decisions about compressor operation and cooling cycles. When the board detects a signal outside the expected parameters, it logs error code 05 and may alter or suspend normal operation to protect the appliance.

The diagnostic process begins at the main PCB connector CN40, specifically between pin #1 (YELLOW wire) and pin #2 (YELLOW wire). A healthy sensor circuit will produce a voltage reading within the range of 1.0V to 4.5V at this connector. A reading outside this range points to a problem somewhere in the sensor circuit, which could include a broken or shorted wire, a disconnected or corroded connector, or a failed sensor element itself.

The most common root causes fall into two categories: mechanical connection failures and sensor element failures. Connection issues include a missing connector, contact corrosion causing high resistance, or a wire that has been pinched or cut. Sensor element failures occur when the thermistor inside the ambient sensor drifts out of calibration or fails entirely, producing an open or short circuit. Identifying which category applies requires checking the CN40 voltage first, then inspecting the wiring harness and connector before condemning the sensor.

Source: manufacturer service documentation.

Common causes of 05

  1. 01

    Loose or disconnected connector at CN40

    Wiring / connection

    The connector at main PCB CN40 may have come loose or was never fully seated, resulting in no signal from the ambient sensor. Inspect the connector for a secure, fully engaged fit and check for bent or pushed-back terminals.

  2. 02

    Corroded or failed connector contacts

    Wiring / connection

    Moisture or oxidation on the CN40 connector pins can cause high resistance or intermittent contact failure, producing a voltage reading outside the 1.0V to 4.5V range. Visually inspect the terminals for discoloration, corrosion, or physical damage.

  3. 03

    Damaged wiring harness

    Part replacement

    A wire in the ambient sensor circuit may be cut, pinched, or shorted against a metal edge, disrupting the signal to the main PCB. Trace the harness from CN40 to the sensor and look for visible damage, chafing, or burn marks.

  4. 04

    Failed ambient air temperature sensor

    Part replacement

    The thermistor in the ambient sensor can fail open or short internally, causing the voltage at CN40 to fall outside the 1.0V to 4.5V window. If the wiring and connector check out, the sensor itself needs to be replaced.

  5. 05

    Faulty main PCB

    Part replacement

    If the wiring, connector, and sensor all test correctly but the voltage at CN40 is still out of range, the main PCB may have a defective input circuit for the ambient sensor. This is the least likely cause and should be considered only after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about 05

What does 05 mean on a LG refrigerator?
Error code 05 on an LG refrigerator signals a fault in the ambient air temperature sensor circuit. The main PCB has detected a voltage reading outside the 1.0V to 4.5V range at connector CN40, which is used to monitor the air temperature around the outside of the unit. This can be caused by a missing connector, contact failure, a cut or shorted wire, or a failed sensor. The refrigerator needs to be diagnosed and repaired to restore normal operation.
Can I fix error code 05 on my LG refrigerator myself?
Some causes of error code 05 are DIY-friendly, such as reseating a loose connector at CN40 or inspecting the wiring harness for obvious damage. However, testing the voltage at the PCB connector requires a multimeter and basic electrical knowledge. If the sensor needs to be replaced or the wiring harness is damaged, comfort with appliance disassembly is required, and some homeowners prefer to hire a technician for those steps.
Is it safe to keep using my LG refrigerator while error code 05 is showing?
Error code 05 means the refrigerator is not receiving accurate ambient temperature data, which can affect how the compressor and cooling system are managed. Food safety could be at risk if the appliance is not maintaining proper temperatures. It is best to check that internal temperatures remain in the safe range using a thermometer and to address the error promptly rather than leaving it unresolved.
How much does it cost to repair error code 05 on a LG refrigerator?
If the fix is as simple as reseating a connector, there may be no parts cost at all. Replacing the ambient air sensor typically falls in the range of $20 to $60 for the part. If a technician is needed, labor costs generally add $80 to $200 depending on the service provider and region. A damaged wiring harness repair can vary more widely depending on the extent of the damage.
Will resetting my LG refrigerator clear error code 05?
Resetting the refrigerator by unplugging it for a few minutes may temporarily clear the error code from the display, but it will return if the underlying problem in the ambient sensor circuit has not been fixed. A reset is useful for confirming whether a fault is persistent, but it is not a repair. The voltage at CN40 should be tested and the sensor circuit inspected to find and correct the actual cause.

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