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Error code reference

LG Refrigerator Error Code E Sd

Communication error between Display PCB Micom and Sub PCB Micom.

LG codesLG refrigerator codes

Communication error between Display PCB Micom and Sub PCB Micom.

First step from the service manual

Check loose connections, then check voltage at CON1/CON5 and CON102/CON101 pins.

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

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What E Sd means on a LG refrigerator

The E Sd error code on an LG refrigerator indicates a communication failure between the Display PCB Micom (the main control board managing the user interface) and the Sub PCB Micom (a secondary control board handling additional refrigerator functions). These two boards communicate continuously to coordinate temperature settings, display output, and operational commands. When that communication link is interrupted or fails to respond within expected parameters, the refrigerator logs the E Sd fault and may restrict normal operation.

The most common entry point for diagnosing this error is the wiring harness that connects the two boards. Loose, corroded, or damaged connectors at CON1 and CON5 on one board, and CON102 and CON101 on the other, are frequent culprits. A technician should inspect these connectors for bent pins, moisture intrusion, or poor seating before proceeding further. Voltage checks at these connector pins will confirm whether the communication signal is present and within spec.

If the connectors and wiring check out, the fault typically points to a failed Display PCB or Sub PCB. One board may have stopped transmitting or receiving the communication signal entirely, either due to component-level failure or power supply issues affecting the boards. In some cases, a power surge or brownout can corrupt board firmware or damage communication circuitry, requiring board replacement rather than a simple repair.

Source: manufacturer service documentation.

Common causes of E Sd

  1. 01

    Loose or disconnected wiring harness connectors

    Wiring / connection

    The connectors at CON1/CON5 and CON102/CON101 can work loose over time from vibration or handling. Reseating these connectors is the first step and resolves the error in many cases.

  2. 02

    Corroded or damaged connector pins

    Wiring / connection

    Moisture or oxidation on the pins at the communication connectors can degrade the signal between the two boards. Inspect pins closely for discoloration, corrosion, or physical damage.

  3. 03

    Damaged wiring harness

    Part replacement

    The wiring between the Display PCB and Sub PCB may have a break, pinch, or short caused by routing wear or rodent damage. A continuity test of the harness will confirm this.

  4. 04

    Failed Display PCB Micom

    Part replacement

    If voltage and wiring check out at all connector points, the Display PCB itself may have failed and is no longer generating or receiving the communication signal. Board replacement would be required.

  5. 05

    Failed Sub PCB Micom

    Part replacement

    The Sub PCB can fail independently, causing it to stop responding to communication from the Display PCB. This is confirmed after ruling out wiring issues and verifying the Display PCB is functional.

See the test procedure for each cause

Frequently asked questions about E Sd

What does E Sd mean on a LG refrigerator?
E Sd indicates a communication error between the Display PCB Micom and the Sub PCB Micom inside the refrigerator. These two control boards must communicate continuously to operate the unit correctly. When that communication is lost or interrupted, the refrigerator logs this fault code. The issue can stem from loose connectors, damaged wiring, or a failed control board.
Can I fix the E Sd error myself?
A homeowner comfortable with basic appliance work can start by unplugging the refrigerator, locating the wiring harness connectors between the two control boards, and reseating them firmly. If the error returns after this, voltage testing and board diagnosis require more advanced skills and tools. At that point, calling a qualified appliance technician is recommended.
Will resetting the refrigerator clear the E Sd error?
A reset, performed by unplugging the unit for several minutes and restoring power, may temporarily clear the E Sd code if the fault was caused by a transient communication glitch. However, if there is an underlying issue such as a loose connector or failed board, the error will return. A reset alone should not be considered a fix.
Is it safe to keep using my refrigerator when E Sd is displayed?
A communication failure between control boards can affect how the refrigerator manages temperature and other functions, which may compromise food safety over time. It is best not to rely on the unit for long-term food storage until the error is diagnosed and resolved. Check the internal temperature with a thermometer to assess whether cooling is still operating normally in the meantime.
How much does it cost to repair an E Sd error on an LG refrigerator?
If the fix is simply reseating a loose connector, the cost is minimal, mostly a service call fee ranging from $75 to $150. If a wiring harness needs replacement, costs typically fall in the $100 to $250 range including parts and labor. Control board replacement is more expensive, generally ranging from $200 to $500 or more depending on the specific board and labor rates in your area.

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