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Error code reference

LG Refrigerator Error Code 4

Fan motor system abnormality in R compartment

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Fan motor system abnormality in R compartment - contact failure on the feedback signal line, motor wire missing, or defect of the motor itself when operating the relevant fan motor.

First step from the service manual

Check feedback signal line for contact failure, check motor wire connection, and test the R compartment fan motor.

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

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What 4 means on a LG refrigerator

Error code 4 on an LG refrigerator indicates a fan motor system abnormality in the R compartment (refrigerator compartment). The control board monitors each fan motor through a dedicated feedback signal line, which continuously reports motor rotation speed back to the board. When the board detects that the feedback signal is absent, intermittent, or outside the expected parameters during fan motor operation, it triggers error code 4 and typically shuts down or limits cooling to protect the system.

The three primary failure points for this error are the feedback signal line connection, the motor wiring harness, and the fan motor itself. A contact failure on the feedback signal line is the most common culprit, often caused by a loose connector, corroded terminal, or damaged wire at the harness junction. A missing or broken motor wire will similarly interrupt the feedback circuit. If the wiring and connectors are intact, the fan motor itself may have failed internally, whether due to a seized bearing, a burned winding, or a defective hall sensor that generates the feedback pulse.

Diagnosing this error requires a systematic approach starting at the wiring connections. Technicians should inspect the feedback signal line connector at both the motor and control board ends for secure seating and clean contacts. The motor wire harness should be checked for pinched, cut, or loose wires. If connections are confirmed good, the fan motor can be tested directly by checking for proper voltage supply and confirming the feedback signal output during operation.

Source: manufacturer service documentation.

Common causes of 4

  1. 01

    Loose or corroded feedback signal line connector

    Wiring / connection

    The connector linking the fan motor's feedback signal wire to the control board can work loose over time or develop corrosion at the terminals. Inspect the connector at both ends for proper seating and clean contact surfaces.

  2. 02

    Disconnected or damaged motor wire

    Wiring / connection

    A wire in the fan motor harness may be broken, pinched, or pulled free from its connector. Visually trace the wiring from the motor to the control board and check for any obvious damage or disconnection.

  3. 03

    Failed R compartment fan motor

    Part replacement

    The fan motor itself may have failed due to a seized bearing, burned winding, or defective internal hall sensor that produces the feedback pulse. A motor that runs intermittently or not at all after confirming good wiring will typically need replacement.

  4. 04

    Faulty control board feedback circuit

    Part replacement

    If the wiring and motor both test correctly, the control board's feedback signal input circuit may be defective, preventing it from reading a signal that is actually present. This is the least common cause and is typically diagnosed after ruling out all wiring and motor issues.

See the test procedure for each cause

Frequently asked questions about 4

What does 4 mean on a LG refrigerator?
Error code 4 on an LG refrigerator indicates a fan motor system abnormality in the R (refrigerator) compartment. The control board has detected a problem with the feedback signal from the compartment fan motor, which can be caused by a loose signal line connection, a missing or damaged motor wire, or a defective fan motor. The refrigerator may experience reduced or absent cooling in the fresh food section while this error is active.
Can I fix LG error code 4 myself?
Some causes of error code 4 are accessible to a knowledgeable DIYer. Checking and reseating the fan motor wiring connectors and inspecting the harness for damaged wires does not require special tools. However, if the fan motor itself has failed, replacing it requires disassembling interior panels and working with electrical components, which may be better suited to a technician if you are not comfortable with appliance repair.
Is it safe to keep using my LG refrigerator with error code 4?
Continuing to use the refrigerator with error code 4 is not recommended for an extended period. If the R compartment fan motor is not operating correctly, the fresh food section will not maintain safe temperatures, putting food at risk of spoilage. Address the error as soon as possible to avoid food loss or further component damage.
Will resetting my LG refrigerator clear error code 4?
A reset may temporarily clear the error code display, but if the underlying fault such as a loose connection, damaged wire, or failed motor is still present, the code will return once the refrigerator resumes normal operation. A reset is useful for confirming whether the fault is intermittent, but it is not a repair. The root cause must be diagnosed and corrected to permanently clear the code.
How much does it cost to repair LG error code 4?
Repair costs depend on the root cause. If the issue is simply a loose connector or damaged wire, costs may only involve a service call fee, typically in the range of $75 to $150. If the R compartment fan motor needs replacement, parts and labor combined often range from $150 to $350 depending on the specific model and local labor rates. Diagnosing the exact failure point before ordering parts is the best way to avoid unnecessary expenses.

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