Whirlpool Refrigerator Error Code CO — What It Means & How to Fix It

What Does This Error Mean?

The CO error on a Whirlpool refrigerator means a communication error between the main control board and the display or user interface board. Modern refrigerators have two separate circuit boards that talk to each other constantly. When one board stops receiving signals from the other, CO appears. This can be caused by a loose wire connection, a power surge, or a failing board. A reset often fixes it — if not, one of the boards likely needs replacement.

Affected Models

Whirlpool WRF535SWHZ
Whirlpool WRS325SDHZ
Whirlpool WRF767SDHZ
Whirlpool WRB322DMBM
Whirlpool WRF560SMHZ

Common Causes

Loose or partially disconnected communication wire between the two control boards
Power surge that corrupted one or both control boards
Failed main control board unable to send or receive communication signals
Failed user interface (display) board unable to communicate with the main board
Damaged wiring harness between the boards caused by vibration or rodent damage

How to Fix It

Perform a hard reset. Unplug the refrigerator from the wall outlet for at least 5 minutes. Then plug it back in. Power fluctuations and brief outages can cause communication errors between the boards that a reset clears permanently.

Make sure to fully unplug — not just press the power button if your model has one. The boards need complete power removal to reset.
Inspect the communication wire harness. On most Whirlpool French door and side-by-side models, a ribbon cable or wire harness runs from the main control board (at the back bottom of the fridge) up to the display board in the door or top panel. Check for any pinched, kinked, or damaged sections.

Accessing the harness may require removing the rear access panel or the control panel cover. Unplug first.
Check both ends of the communication harness at each board. Unplug and firmly reseat each connector. Connectors can slowly loosen over time from vibration. A connector that feels slightly loose when you push it in likely worked its way loose gradually.

Never force a connector — if it doesn't seat easily, check that you have the correct connector for that socket.
Check your home circuit breaker for the refrigerator. A weak or failing breaker can cause partial power delivery, which confuses the control boards. Reset the breaker by flipping it fully off and then back on. Also try plugging the refrigerator into a different outlet temporarily if possible.

Refrigerators should be on a dedicated 15 or 20-amp circuit and should not share an outlet with other appliances.
If the CO error persists after the above steps, have a technician test both the main control board and user interface board. They can simulate communication between the boards with a service tool to identify which one is not responding correctly.

Provide the technician with your full model and serial number (inside the fridge on the door frame sticker) for faster service.

When to Call a Professional

If a reset doesn't fix CO, a technician should diagnose which board has failed. Replacing the wrong board wastes money — a technician can identify the faulty component. Main control boards cost $150-$350. Display boards typically cost $75-$200. Consider the age of the refrigerator before committing to an expensive repair.

Frequently Asked Questions

Can a power outage cause the CO error?

Yes — power outages and surges are a very common cause of communication errors on modern refrigerators. The sudden loss and restoration of power can corrupt the startup sequence of one or both control boards. Always try a full 5-minute unplug reset after any power outage before assuming a board has failed. A surge protector or UPS for your refrigerator can prevent future power-related errors.

Will CO affect my food temperature?

It can. If the main board and display board can't communicate, the refrigerator may not regulate temperature correctly. Check your food temperatures with a thermometer — safe refrigerator temperature is 35-38°F (2-3°C). If temperatures are normal, the CO error may be cosmetic (display only) until you can get it repaired.

Is CO the same as CF on Whirlpool refrigerators?

They are similar but not identical. CO typically refers to a communication failure between two specific boards. CF (Communication Failure) is a more general communication fault code that may involve additional components. Both are treated similarly in terms of diagnosis — start with a reset and then check wiring connections between boards.