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Error code reference

Kenmore Refrigerator Error Code Er CO1

Communication error

Kenmore codesKenmore refrigerator codes

Communication error — short or open lead wire between Main PCB and Display PCB.

First step from the service manual

Check wiring between Main PCB and Display PCB for short or open circuits.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What Er CO1 means on a Kenmore refrigerator

The Er CO1 error code on a Kenmore refrigerator signals a communication failure between the Main PCB (printed circuit board) and the Display PCB. These two boards exchange data continuously over a dedicated lead wire harness. When that signal is interrupted by a short circuit or an open circuit in the wiring, the control system detects the break in communication and triggers this error to alert the technician that the data link has been compromised.

The most common physical causes involve the wiring harness that connects the two boards. A short circuit occurs when two conductors in the harness make unintended contact, often due to pinched, chafed, or melted insulation. An open circuit occurs when continuity is fully broken, typically from a loose connector, a pulled terminal, or a physically severed wire. Both conditions produce the same Er CO1 fault because the Main PCB receives no valid signal from the Display PCB regardless of whether the line is shorted or open.

Diagnosing this code starts with a thorough visual inspection of the entire wire harness running between the Main PCB and the Display PCB. Look for pinch points at door hinges or cabinet edges, damaged insulation, corroded connector pins, and unseated connector housings. A multimeter set to continuity mode can confirm whether each conductor in the harness is intact and free of shorts. If the wiring checks out, the Display PCB itself may be faulty and unable to communicate, or the Main PCB may have a damaged communication port.

Source: manufacturer service documentation.

Common causes of Er CO1

  1. 01

    Loose or unseated wire connector

    Wiring / connection

    The connector plugging the harness into either the Main PCB or the Display PCB may have worked loose over time due to vibration. Inspect both ends of the harness and press each connector firmly until it clicks into place.

  2. 02

    Damaged or pinched harness wire

    Part replacement

    The lead wire harness can become pinched at door hinges or cabinet edges, cutting through insulation and causing a short or open circuit. Inspect the full length of the harness for visible damage, chafing, or crushed sections.

  3. 03

    Corroded or burnt connector terminals

    Part replacement

    Moisture or heat exposure can corrode the metal terminals inside the connector housing, increasing resistance until communication fails entirely. Check each terminal for discoloration, oxidation, or heat damage.

  4. 04

    Faulty Display PCB

    Part replacement

    If the wiring harness tests good with a multimeter and all connectors are secure, the Display PCB itself may have an internal failure that prevents it from communicating with the Main PCB. Board replacement would be required.

  5. 05

    Faulty Main PCB

    Part replacement

    In cases where the harness and Display PCB both check out, the communication port or circuitry on the Main PCB may be damaged. This is the least common cause and is typically diagnosed after all other components have been ruled out.

See the test procedure for each cause

Frequently asked questions about Er CO1

What does Er CO1 mean on a Kenmore refrigerator?
Er CO1 is a communication error indicating that the Main PCB and the Display PCB have lost contact with each other. The fault is caused by a short circuit or open circuit in the lead wire harness connecting the two boards. The refrigerator's control system detected the break in the data signal and triggered this code to indicate the wiring or a board needs to be inspected.
How do I fix the Er CO1 error on my Kenmore refrigerator?
Start by unplugging the refrigerator and inspecting the wire harness between the Main PCB and the Display PCB for loose connectors, pinched wires, or visible damage. Reconnect any loose connectors and test the harness conductors with a multimeter for continuity and shorts. If the harness is intact, the Display PCB or Main PCB may need to be replaced.
Is it safe to keep using my refrigerator while the Er CO1 code is showing?
A communication error between the control boards can affect the refrigerator's ability to properly regulate temperature and respond to control inputs. It is best to address the fault promptly rather than continuing to run the unit. Food safety could be at risk if temperature control is impaired.
Will resetting my Kenmore refrigerator clear the Er CO1 error?
Unplugging the refrigerator for a few minutes may temporarily clear the error, but the code will return if the underlying wiring fault or board failure is not corrected. A reset does not repair a short circuit, open circuit, or damaged component. A proper diagnosis and repair of the wiring harness or affected board is required to resolve the error permanently.
How much does it cost to repair the Er CO1 error on a Kenmore refrigerator?
Repair costs depend on what needs to be replaced. If the fix is simply reseating a connector or replacing a damaged harness, costs are generally modest, typically in the range of $50 to $150 for parts and labor. If the Display PCB or Main PCB needs replacement, costs can rise to the $150 to $400 range depending on parts pricing and local labor rates.

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