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Error code reference

LG Refrigerator Error Code 25

Uart communication error with PLC modem (electric power line communication error)

LG codesLG refrigerator codes

Uart communication error with PLC modem (electric power line communication error). PLC modem applied optionally; if appliance does not use PLC, this error display is not a defect.

First step from the service manual

Check PLC modem communication; verify if PLC modem option is applied to the model.

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

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What 25 means on a LG refrigerator

Error code 25 on an LG refrigerator indicates a UART communication failure between the main control board and the PLC (Power Line Communication) modem. UART, which stands for Universal Asynchronous Receiver-Transmitter, is a serial communication protocol used to transfer data between internal components. In models equipped with a PLC modem, this modem allows the refrigerator to communicate data over the home's existing electrical wiring, enabling features such as remote diagnostics or smart grid interaction. When the main board cannot establish or maintain a valid UART signal with the PLC modem, error code 25 is triggered.

A critical consideration with this error is that the PLC modem is an optional component, not installed on every LG refrigerator model. If your specific model was not built with a PLC modem, the appearance of error code 25 is not considered a defect and does not indicate any functional problem with the refrigerator. Technicians should first confirm whether the unit in question is configured with PLC modem hardware before proceeding with any component-level diagnostics or repairs.

In units that do include the PLC modem, the error is most commonly caused by a loose or damaged communication harness between the modem and the main control board, a failed PLC modem module itself, or a defective main control board that cannot properly process UART signals. Electrical noise or interference on the home's power line can also disrupt PLC communication and trigger this code intermittently.

Source: manufacturer service documentation.

Common causes of 25

  1. 01

    PLC modem not installed on this model

    Wiring / connection

    Many LG refrigerators do not include a PLC modem. If the unit was never equipped with this optional module, error code 25 is a non-defect display and the refrigerator operates normally.

  2. 02

    Loose or damaged communication harness

    Wiring / connection

    The wiring harness connecting the PLC modem to the main control board may have become loose, pinched, or damaged, interrupting the UART data signal. Inspect the connector and harness for continuity and secure seating.

  3. 03

    Failed PLC modem module

    Part replacement

    The PLC modem itself may have failed internally, preventing it from sending or receiving UART signals. A failed modem will need to be replaced to restore communication.

  4. 04

    Defective main control board

    Part replacement

    If the main control board's UART interface is damaged or malfunctioning, it cannot properly communicate with the PLC modem even if the modem and wiring are intact. Board replacement may be necessary.

  5. 05

    Power line interference or electrical noise

    Wiring / connection

    Excessive electrical noise on the home's power line can disrupt PLC communication and cause intermittent appearances of error code 25. This is more likely in homes with older wiring or multiple high-draw appliances sharing the same circuit.

See the test procedure for each cause

Frequently asked questions about 25

What does 25 mean on a LG refrigerator?
Error code 25 on an LG refrigerator indicates a UART communication error with the PLC modem, which is a module that communicates data over the home's electrical wiring. This modem is an optional feature and is not installed on all LG refrigerator models. If your model does not include a PLC modem, this code is not a defect and the refrigerator is functioning normally. If the modem is present, there may be a wiring, modem, or control board issue to investigate.
Will my LG refrigerator still cool properly with error code 25?
Yes, in most cases the refrigerator will continue to cool normally when error code 25 is displayed. The PLC modem is related to communication functions, not the core cooling system. If the error appears on a model without a PLC modem, there is no functional impact at all.
Will resetting my LG refrigerator clear error code 25?
A power reset may temporarily clear error code 25, but the code will return if the underlying communication issue is not resolved. On models without a PLC modem installed, the code may reappear after reset as a persistent non-defect display. On equipped models, clearing the code permanently requires addressing the root cause, such as reseating the harness or replacing the faulty modem.
Is error code 25 on my LG refrigerator a safety concern?
Error code 25 does not indicate a safety hazard. It is a communication error related to an optional networking module and does not affect the electrical safety or structural integrity of the refrigerator. If the code appears without a PLC modem being installed, it can be disregarded entirely.
How much does it cost to fix error code 25 on an LG refrigerator?
If the refrigerator does not have a PLC modem, no repair is needed and there is no cost involved. For models with the modem installed, costs depend on the faulty component. PLC modem replacement parts typically range from $50 to $150, while main control board replacement can range from $100 to $300 or more, not including labor fees if a technician is hired.

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