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Error code reference

Kenmore Refrigerator Error Code Er CO

Communication error between MICOM of Main PCB and Display MICOM; caused by poor communication connection, poor TR of transmitter/receiver Tx/Rx…

Kenmore codesKenmore refrigerator codes
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What the Er CO error code actually means

Your Kenmore refrigerator is displaying this error because the two main computer boards inside the unit have lost the ability to communicate with each other. Think of it like two parts of the refrigerator's brain that need to constantly send messages back and forth, and that connection has been interrupted. This is typically caused by a loose wire connection, a damaged cable, or a failed component on one of the boards.

Diagnostic procedure

The full Er CO procedure

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1
First diagnostic step
Check loose connections, then check Red to White Red at CON101 for 12VDC.
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Most common causes of Er CO

Ranked by how often they cause this code
  1. 1Loose or disconnected wiring harness at CON101
  2. 2Failed Tx/Rx communication circuit on main PCB or display board
  3. 3Damaged or shorted wiring harness between display and main board
  4. 4No 12VDC output at CON101 due to main PCB power supply failure

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Questions people ask about Er CO

What does Er CO mean on a Kenmore refrigerator?
Er CO stands for a communication error between the main control board's microcontroller (Main MICOM) and the display board's microcontroller (Display MICOM). The two boards send signals back and forth continuously, and when that link is interrupted by a loose connector, damaged wiring, or a failed transmitter/receiver circuit, the error appears. It is not a sensor failure or a compressor fault.
Is it safe to use my Kenmore refrigerator while it shows Er CO?
The refrigerator may continue cooling temporarily while Er CO is active, but the communication failure means the display controls and temperature management functions may not be operating reliably. You should not depend on the refrigerator to maintain safe food storage temperatures until the error is resolved. Check the actual temperature inside with a thermometer and plan to address the repair promptly.
Will unplugging and replugging my Kenmore refrigerator clear the Er CO code?
A power reset may temporarily clear Er CO if the communication dropout was caused by a momentary glitch, but if the underlying issue is a loose connector, damaged harness, or failed board component, the code will return. Use the reset as a first step to confirm whether the error is persistent, then proceed with checking CON101 and the wiring harness.
How do I fix Er CO on a Kenmore refrigerator?
Start by unplugging the refrigerator and inspecting the wiring harness connector at CON101 on the main PCB. Reseat any loose connectors and check the harness for visible damage. After reconnecting power, check for 12VDC on the Red to White-Red wires at CON101. If voltage is present and the error persists, the Tx/Rx communication circuit on the main board or display board has likely failed and one or both boards will need replacement. If there is no 12VDC at CON101, the main board itself may need to be replaced.
How much does it cost to fix Er CO on a Kenmore refrigerator?
If the fix is simply reseating a loose connector at CON101, there is no parts cost. If the wiring harness is damaged, a replacement harness typically runs between $20 and $60. If the main PCB or display board needs replacement, parts range from $80 to $250 or more depending on the specific model, plus labor if you use a technician. Confirming 12VDC at CON101 before ordering parts helps avoid replacing the wrong component.

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