LG · Refrigerator
LG Refrigerator CO Error Code
Communication fault on main board
What this error means
CO indicates Communication Error between the main refrigerator PCB and a sub-board—display, inverter compressor driver, or door UI. Cooling may continue briefly or stop depending on which link failed.
How CO is detected
When CO appears on a LG refrigerator, the control board has confirmed that water did not leave the machine within the programmed drain window. On LG LFXS28968S, LG LRFVS3006S, and similar variants, the drain pump runs for a fixed interval—often three to seven minutes on washers and dishwashers—while a pressure switch or turbidity sensor verifies the tub or sump is empty. If water remains, the cycle stops to prevent spin with a full tub or overflow on the next fill.
Most CO calls are resolved without parts: unplug five minutes—avoid opening doors unnecessarily during outage if food safety allows. Restricted drain paths mimic pump failure because the impeller spins against a blocked hose or filter. Document whether the pump hums audibly during the drain step; a humming pump with no water movement points to a clogged filter or kinked hose, while silence may indicate a failed pump motor or loose wiring at the harness.
After clearing blockages, run a short cycle and listen at the drain hose for steady water flow. If CO returns on the next load with a clean filter and straight hose, measure resistance at the pump motor connector per the service manual for your model before ordering a replacement pump assembly.
Common causes
- Loose ribbon cable after door removal for service
- Inverter compressor board disconnect
- Power surge damaging UART communication
- Condensation on connectors in humid kitchens
Step-by-step fixes
- 1Unplug five minutes—avoid opening doors unnecessarily during outage if food safety allows
- 2Ensure the fridge is on a dedicated grounded outlet
- 3Note whether CO appears at startup or randomly mid-day
- 4Avoid extension cords and shared circuits with microwaves
When to call a technician
CO at every power-on after reset typically requires main or inverter board replacement.
Affected models
- LG LFXS28968S
- LG LRFVS3006S
- LG LMXS28626S
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use refrigerators to prevent CO from lint and food debris buildup.
- Record when CO appears in the cycle and whether it clears after a 60-second power reset on your LG refrigerator—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for CO; LG uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting CO; reversed plugs on pumps and valves cause immediate repeat faults.