Er CO Serious Hard — consider a tech

LG Refrigerator Er CO — Compressor / Communication Fault

LG Refrigerator · Error code Er CO

What Er CO Means

Er CO (also shown as E CO) is a communication error: the main control board has lost communication with the display PCB. Per LG it can be caused by a failed main board or display board, a disconnected wire, or unstable power. It is not a compressor fault code, and the refrigerator may continue cooling while it is displayed.

Symptoms

  • Fridge and freezer warming
  • Compressor not running
  • Er CO on the display

Common Causes

1
Loose or disconnected communication wiring

A connector or wire in the harness between the main control board and the display PCB is loose, damaged, or disconnected.

2
Failed main board or display PCB

Either board can fail and drop communication; a power surge or unstable supply voltage can also trigger the fault.

How to Fix It

  1. Unplug the refrigerator (or trip its breaker) for about 5 minutes, then restore power to clear a communication glitch — this is LG's recommended first step.
  2. If you are comfortable doing so, check the wiring harness between the main control board (rear of the cabinet) and the display PCB for loose or damaged connectors.
  3. If Er CO returns after the power reset, LG advises having the unit checked by a service technician — the main board or display PCB likely needs replacement.

Parts You May Need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

Common replacement LG refrigerator main control board (PCB, model-specific) View on Amazon→ Common replacement LG refrigerator display board assembly (model-specific) View on Amazon→

More LG Refrigerator Codes

22 22 — Compressor relay / inverter control fault 33 33 — Compressor / defrost test fault 67 67 — Door open / not fully closed 88 88 — Power-on display test (not a fault) Er CF Er CF — Condenser Fan Fault Er dH Er dH — Defrost Heater Fault

All LG codes → All refrigerator codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.