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Error code reference

LG Refrigerator Error Code E rt

Room (ambient) temperature sensor error

LG codesLG refrigerator codes

Room (ambient) temperature sensor error - external/room temperature sensor has a short, open, or out-of-range resistance reading.

First step from the service manual

Check for a loose connection between Main PCB and sensor at CON5 pins 13-14.

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

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What E rt means on a LG refrigerator

The E rt error code on an LG refrigerator indicates a fault in the room temperature sensor, also called the ambient temperature sensor. This sensor monitors the environmental temperature surrounding the refrigerator and feeds that data to the main PCB so the control board can adjust compressor cycles and cooling output accordingly. When the board detects a short circuit, an open circuit, or a resistance reading outside the acceptable range from this sensor, it logs the E rt code and may alter or suspend normal operation.

The main PCB communicates with the room temperature sensor through connector CON5, specifically pins 13 and 14. A fault at this interface is the most common starting point for diagnosis. The board continuously reads the sensor's resistance value and compares it against expected parameters for the current operating conditions. A short will drive resistance toward zero ohms, while an open circuit will push it toward infinite resistance. Either condition falls outside the expected range and triggers the error.

Common causes include a loose or corroded connection at CON5 pins 13-14, a damaged wiring harness between the sensor and the board, and a failed sensor itself. Because the sensor is exposed to temperature fluctuations and occasional moisture, the connector pins can oxidize over time, increasing resistance at the contact point and producing intermittent or persistent faults. Replacing a failed sensor is a straightforward repair, but thorough connector inspection should always come first.

Source: manufacturer service documentation.

Common causes of E rt

  1. 01

    Loose connection at CON5 pins 13-14

    Wiring / connection

    A loose or partially disconnected connector at pins 13 and 14 of CON5 on the main PCB is the most frequent cause of the E rt error. Inspect the connector for any signs of backing out, poor seating, or bent pins.

  2. 02

    Corroded or oxidized connector pins

    Wiring / connection

    Moisture and temperature cycling can cause oxidation on the CON5 connector pins, increasing contact resistance and causing the board to read an out-of-range value. Look for discoloration, white or green deposits, or rough texture on the pin surfaces.

  3. 03

    Damaged wiring harness

    Part replacement

    The wire harness running between the room temperature sensor and the main PCB can develop breaks, pinches, or chafing over time, producing an open or intermittent circuit. Trace the harness carefully and check for any visible damage to the insulation or conductors.

  4. 04

    Failed room temperature sensor

    Part replacement

    The sensor itself can fail due to an internal short or open, producing a resistance value outside the acceptable range regardless of actual ambient temperature. If the wiring and connections check out, measure the sensor resistance and compare it to the specified range before replacing.

  5. 05

    Faulty main PCB

    Part replacement

    If the sensor and all wiring measure correctly but the error persists, the main PCB may have a defective input circuit at CON5 that is misreading a valid 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 E rt

What does E rt mean on a LG refrigerator?
The E rt code indicates a fault with the room temperature sensor, also called the ambient temperature sensor. The main control board has detected a short, open circuit, or an out-of-range resistance reading from that sensor. This sensor helps the refrigerator regulate its cooling cycles based on the surrounding environment. The error requires inspection of the sensor, its wiring, and the connector at CON5 pins 13-14 on the main PCB.
Can I fix the E rt error myself?
Many cases of the E rt error can be resolved without professional help by inspecting and reseating the connector at CON5 pins 13-14 on the main PCB. If the connection looks clean and secure, the next step is testing or replacing the room temperature sensor, which is a relatively accessible component. However, if the fault points to the main PCB itself, that replacement is more involved and may benefit from professional service.
Is it safe to keep using my refrigerator while the E rt error is showing?
The refrigerator may continue to run with the E rt code present, but its ability to optimize cooling based on room conditions may be compromised. Food safety depends on whether the refrigerator is maintaining correct internal temperatures, so monitor those closely with a thermometer. It is best to address the error promptly rather than leaving it unresolved for an extended period.
How much does it cost to repair the E rt error on an LG refrigerator?
If the fix is simply reseating a loose connector, the repair costs nothing beyond your time. A replacement room temperature sensor typically costs in the range of $15 to $50 for the part. If a wiring harness or main PCB replacement is needed, total repair costs including labor can range from $100 to $400 or more depending on the specific model and service rates in your area.
Will resetting my LG refrigerator clear the E rt error code?
A power reset may temporarily clear the E rt code, but the error will return if the underlying fault with the room temperature sensor or its wiring has not been fixed. Resetting the unit is useful for confirming whether the fault is intermittent, but it is not a lasting solution. A proper repair requires diagnosing and correcting the sensor, connector, or wiring issue causing the fault.

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