Display and Main Board Communication Error
What it means
This code appears on LG refrigerators with a digital display and means the display board and the main board are not exchanging signals properly. The cause is usually the wiring between them; on models with the display on the door, this wiring runs through the door hinge and gets flexed. The refrigerator may keep cooling, but the display and buttons do not respond properly; the same code can mean something else on other brands.
Models covered: LG refrigerators with a digital display (e.g. side-by-side, French door and top-freezer models); the code shows as Er plus two letters.
Symptoms4
- Er CO shows on the refrigerator display.
- Buttons do not respond or settings are not saved.
- The display flickers or goes off and comes back.
- Cooling or the water and ice dispenser may behave oddly on some models.
Possible causes5
- Loose or corroded connectors on the wiring between the display and main board.
- Broken or worn wires at the door hinge from repeated opening and closing.
- Moisture or condensation inside the display board.
- Failed display board.
- Failed main board, often after a power surge.
How to diagnose5
- Unplug the refrigerator for a few minutes and plug it back in; the code may clear if it came from a brief power disturbance.
- Notice whether the code appears or clears when the door is opened or closed; this points to the wiring through the hinge.
- Make sure the refrigerator is on a sound socket, and consider a voltage protector if power is unstable.
- A technician unplugs the refrigerator before opening any cover, then checks the connectors and wiring from the display to the main board, including the hinge area.
- If the wiring is good, the technician finds which board is faulty using the manufacturer's test method.
How to fix5
- Clean and reseat corroded connectors.
- Repair or replace broken wires at the door hinge.
- Dry the display board of moisture, and replace it if damaged.
- Replace the main board if it is proven to be the cause.
- Run the refrigerator and confirm the display and buttons work normally without the code returning.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 100–1,500 (≈ USD 27–400)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
The cost is low for a connector or wire, moderate for a new display board, and highest when the main board must be replaced.
Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026
Frequently asked questions
Will the refrigerator stop cooling with this code?
Not always; it may keep cooling on its previous settings, but you cannot rely on that. Watch how cold the food stays and have it checked soon.
Why is the code linked to opening and closing the door?
On many models the wiring between the display and main board runs through the door hinge, and over time it can wear or break from repeated flexing.
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