ApplianceErrors.com

LG Refrigerator Error Code Er CO

Reviewed by the ApplianceErrors Editorial Team · Verified against manufacturer service documentation · Last verified: June 10, 2026
⚠ Medium Severity 🔧🔧🔧 Advanced DIY

Communication error — main board to sub-board

The most common cause of the Er CO error on a LG refrigerator is wire harness connector loose between boards (~50% of cases); start with: power cycle the refrigerator.

💰 DIY cost: $60–$150 👨‍🔧 Pro cost: $250–$480 Save $190+ by doing it yourself
LG Refrigerator error code Er CO on the display panel
How the Er CO code appears on a LG refrigerator display

What Does Error Code Er CO Mean on a LG Refrigerator?

Communication error — main board to sub-board.

The main control board has lost communication with the display/sub-board, so temperature settings, diagnostics, or ice/water controls may stop responding. A loose harness between the door/display board and the main board is most common; a failed sub-board or main board comes next.

What Causes Error Code Er CO?

Here are the most common causes in order of frequency. Start with the most likely cause before moving to the next:

  1. 1
    Wire harness connector loose between boards 50% of cases
  2. 2
    Door/display sub-board failure 25% of cases
  3. 3
    Main control board communication fault 15% of cases
  4. 4
    Harness wire broken at door hinge 10% of cases

How to Fix LG Refrigerator Error Code Er CO

🔧🔧🔧 Advanced DIY Est. time: 1–3 hours
⚡ Safety first: Unplug the appliance before opening any panels or touching internal components.
  1. 1

    Power cycle the refrigerator

    Unplug for 10 minutes so both boards reset, then restore power and check whether the display responds.

  2. 2

    Reseat board connectors

    Check and reseat the multi-pin connectors at the main board, display/sub-board, and door hinge harness.

    ⚠️ Unplug before accessing control boards.
  3. 3

    Inspect the hinge harness

    Look for pinched or broken wires where the door harness flexes; repair or replace any damaged harness.

  4. 4

    Replace the sub-board first

    If the wiring is sound, replace the cheaper display/sub-board before condemning the main control board.

    🔩 LG refrigerator sub-board ($60–$150)

How to Reset Error Code Er CO

Unplug the refrigerator for 10 minutes, then restore power; if Er CO returns, reseat the display, door-hinge, and main-board connectors before replacing any board, because a loose harness is the most common fix.

Note: If the error returns after resetting, the underlying issue has not been resolved. Work through the fix steps above.

Full LG refrigerator reset guide → Enter diagnostic mode →

Did this guide fix your appliance?

When to Call a Professional

Call a technician if Er CO persists after connectors are reseated, since isolating a broken door harness from a failed sub-board or main board requires live diagnostic checks and access to multiple control modules.

Average professional repair cost for this issue: $250–$480

Related Error Codes

Er FF
Freezer fan error — fan motor not operating
⚠ High Severity

Find Replacement Parts

Use these links to find the exact replacement parts for your LG Refrigerator:

🔩
Search PartSelect
LG Refrigerator repair parts
🔧
Search RepairClinic
Step-by-step video guides

External links — ApplianceErrors.com is not affiliated with these retailers.

More LG Refrigerator Error Codes

Er dH Defrost heater error — defrost cycle not completing Er CF Condenser fan motor error Er FS Freezer temperature sensor error Er IS Ice maker sensor failure Er IF Ice maker fan error dS Defrost sensor open circuit

Frequently Asked Questions

Can I keep using my LG Refrigerator when error Er CO appears? +
You often can for a cycle or two, but the control-board issue behind Er CO will keep interrupting normal operation until it is fixed. Plan the repair rather than ignoring the code.
What most commonly causes Er CO on a LG Refrigerator? +
Across reported LG refrigerator repairs, the most frequent is wire harness connector loose between boards (50% of cases), door/display sub-board failure (25%), then main control board communication fault (15%). Check them in that order before replacing any parts.
Er CO keeps coming back after a reset — what should I check next? +
A reset only clears the stored Er CO fault; if it returns, the control-board problem is still present. Move on to the physical checks — power cycle the refrigerator, then reseat board connectors — since the code will reappear until the root cause is resolved. This is an advanced repair involving deeper disassembly or electrical testing.
How much does it cost to fix LG Refrigerator error Er CO? +
A DIY repair typically runs $60–$150 in parts, versus $250–$480 for a professional service call, so handling it yourself saves around $190. Expect the work to take 1–3 hours.

Sources & References

Content verified against manufacturer service documentation. Last verified: June 10, 2026.

← All LG Refrigerator Error Codes ← All LG Error Codes