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Error code reference

LG Refrigerator Error Code rt E

Ambient/defrost sensor error

LG codesLG refrigerator codes

Ambient/defrost sensor error - ambient 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, defrost controller and sensor at CON7 Pin11 to Pin12.

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

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What rt E means on a LG refrigerator

The rt E error code on an LG refrigerator indicates a fault with the ambient or defrost temperature sensor. This sensor monitors the ambient air temperature around the refrigerator and plays a role in coordinating the defrost cycle through the defrost controller. The Main PCB reads resistance values from this sensor to determine operating conditions. When the PCB detects a short circuit, an open circuit, or a resistance reading that falls outside the expected range, it triggers the rt E code to alert the user and technician to a sensor circuit failure.

The sensor circuit runs between the Main PCB and the defrost controller, with the specific connection point located at CON7, Pin 11 to Pin 12. A loose, corroded, or damaged connector at this location is the first place to inspect, as vibration and thermal cycling over time can work connections loose. If the connector checks out, the sensor itself may have failed internally, producing either no resistance reading (open circuit) or a very low resistance reading (short circuit), both of which fall outside the acceptable operating range.

Left unaddressed, an rt E fault can disrupt the defrost cycle and lead to frost accumulation on the evaporator coil, reduced cooling efficiency, or complete loss of cooling. Diagnosing this error requires a multimeter to check continuity and resistance across the sensor terminals and the wiring harness between the sensor and CON7 on the Main PCB. If wiring and connectors test good but the fault persists, the sensor or Main PCB may require replacement.

Source: manufacturer service documentation.

Common causes of rt E

  1. 01

    Loose or disconnected wiring at CON7 Pin 11 to Pin 12

    Wiring / connection

    The connector between the Main PCB and the defrost controller at CON7 Pin 11 to Pin 12 can work loose over time due to vibration and heat cycles. Inspect this connector first and reseat it firmly before proceeding with further diagnostics.

  2. 02

    Faulty ambient or defrost sensor

    Part replacement

    The sensor itself may have developed an internal open or short circuit, causing resistance readings that fall outside the acceptable range. Use a multimeter to measure resistance across the sensor terminals and compare to the specified range for confirmation.

  3. 03

    Damaged or corroded wiring harness

    Part replacement

    The wiring between the sensor and the Main PCB can suffer from corrosion, pinching, or breaks, particularly in areas exposed to moisture near the evaporator or defrost components. Inspect the full length of the harness for visible damage or corrosion at terminal pins.

  4. 04

    Corroded or damaged connector pins at CON7

    Wiring / connection

    Even if the connector is fully seated, individual pins at CON7 can corrode or bend, creating an intermittent or failed electrical connection. Inspect Pin 11 and Pin 12 closely for corrosion, deformation, or carbon tracking.

  5. 05

    Failed Main PCB

    Part replacement

    If the sensor, wiring harness, and connectors all test within specification, the Main PCB itself may have a fault preventing it from reading the sensor signal correctly. PCB failure is the least common cause and should only be concluded after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about rt E

What does rt E mean on a LG refrigerator?
The rt E code indicates an ambient or defrost sensor error. The Main PCB has detected that the ambient temperature sensor has a short circuit, an open circuit, or a resistance reading outside the acceptable range. This fault affects the refrigerator's ability to properly manage the defrost cycle and can lead to cooling problems if not corrected.
Can I fix the rt E error myself without a technician?
A knowledgeable DIYer can start by checking the wiring connector at CON7 Pin 11 to Pin 12 on the Main PCB, as a loose connection is the most common cause. If reseating the connector does not clear the code, testing the sensor and wiring harness with a multimeter is the next step. Replacing the sensor is a straightforward repair, but if the Main PCB is at fault, professional diagnosis is recommended before purchasing a board.
Is the rt E error dangerous and is it safe to keep using my refrigerator?
The rt E error is not a safety hazard in the traditional sense, but it can compromise the refrigerator's ability to maintain safe food storage temperatures. A disrupted defrost cycle can lead to heavy frost buildup and reduced cooling, which may cause food spoilage. It is best to address this error promptly rather than continuing to rely on the appliance.
Will resetting my LG refrigerator clear the rt E code?
A reset may temporarily clear the rt E code, but the code will return if the underlying fault in the sensor, wiring, or connector has not been corrected. Resetting without repair does not fix the problem and can delay proper diagnosis. Address the root cause at CON7 Pin 11 to Pin 12 or the sensor itself before relying on a reset.
How much does it cost to repair the rt E error on an LG refrigerator?
Repair costs depend on which component has failed. Replacing the ambient or defrost sensor typically costs between $50 and $150 for parts and labor. If the Main PCB requires replacement, costs can range from $200 to $400 or more depending on the model and labor rates in your area. Starting with the connector inspection at CON7 costs nothing and may resolve the issue without any parts expense.

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