LG Freezer CO Error: Communication error between control boards
LG freezer error — here’s what you need to know. The CO error code on your LG freezer indicates a communication error between the main control board and a secondary module. This is a High severity issue. What Does CO Mean on an LG Freezer? The CO code signals that the main control board has […]
~25%
DIY Fixable
From 80
Typical Repair Cost
1–4 hours
Pro Repair Time
Quick Assessment
Answer to continue safely
Is it safe to keep using?
Maybe. The freezer may continue cooling in a limited failsafe mode, but without reliable board communication, temperature control is unpredictable. Monitor temperatures closely and avoid storing critical items until the fault is resolved
Can I reset the code?
Yes. A 10-minute power cycle often clears a CO code caused by a firmware glitch or a brief communication dropout. If a board or harness is physically damaged the code will return on the next startup self-test
When to stop immediately?
Stop if you notice: Display is completely blank and the freezer does not respond to any controls, CO code returns immediately after every power cycle.
Symptoms You May Notice
Control panel display behaves erratically
The display shows incorrect readings, goes blank intermittently, or buttons stop responding because the display board has lost its data link to the main board
Freezer operates inconsistently
The unit may switch between modes unexpectedly or fail to respond to temperature setting changes as the main board cannot relay commands to secondary modules
CO code on the control panel display
The CO fault code is displayed, often appearing after a power fluctuation or when the freezer is first powered on during the board self-test
Inconsistent temperature performance
The freezer runs too hot, too cold, or cycles erratically because the control board receives inaccurate temperature readings from the faulty sensor.
Possible Causes
Loose or damaged inter-board wiring harness
The ribbon cable or wiring harness connecting the main board to the display or inverter board has come loose or developed a break in the data lines
DIY PossibleCorrupted board firmware from power surge
A voltage spike or power outage has corrupted the firmware on one of the boards, causing it to fail the communication handshake at startup
Requires ProfessionalFailed main or secondary control board
One of the electronic boards has developed an internal hardware fault on its communication circuit, requiring board-level diagnosis and replacement
Requires ProfessionalSafe Checks You Can Do
-
1
Power-cycle the freezer
Unplug the freezer from the wall outlet and wait a full 10 minutes before plugging it back in. This allows all board capacitors to discharge and forces a fresh communication initialization sequence
-
2
Check the inter-board harness connectors
With the freezer unplugged, locate the wiring harness connections on the back of the display panel and on the main board (usually behind the rear access panel). Firmly reseat all connectors and check for corrosion or bent pins
-
3
Check the power outlet and surge protector
Plug the freezer directly into a wall outlet (not a power strip or surge protector) and verify the outlet delivers stable voltage. Power fluctuations can repeatedly trigger CO faults
When to Call a Professional
Contact a qualified technician if:
- Code persists after power cycle and harness reseating — board-level diagnosis required
- Wiring harness shows physical damage, kinks, or melted insulation
- A different error code appears after CO clears, suggesting cascading board failure
Need Professional Help?
Find qualified technicians in your area for proper diagnostics and repair.
Freezer Repair Service Schedule Appointment