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Error code reference

Frigidaire Washer Error Code E91

Communication error between the User Interface Board and the Main Control Board.

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Communication error between the User Interface Board and the Main Control Board.

First step from the service manual

Disconnect connector CN3 which connects Main Control Board and Display Board, then check if E91 alarm appears again.

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

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What E91 means on a Frigidaire washer

The E91 error code on a Frigidaire washer indicates a communication failure between the User Interface (UI) Board and the Main Control Board. These two boards continuously exchange data signals during operation, allowing the control board to receive user input commands and send cycle status information back to the display. When this communication link breaks down or produces inconsistent signals, the machine triggers E91 and halts operation to prevent uncontrolled behavior.

The communication between these boards typically travels through a wiring harness connected via connector CN3, which links the Main Control Board to the Display Board. A fault can originate at the connector itself, along the wiring harness, or within either of the two boards. Loose, corroded, or damaged pins at CN3 are among the most common physical causes, since vibration during spin cycles can gradually loosen connector seating over time. Wiring harness damage from pinching, chafing, or moisture intrusion can also interrupt the data signal pathway.

The recommended first diagnostic step is to disconnect connector CN3 and then reconnect it firmly, then observe whether the E91 alarm reappears during operation. If disconnecting and reseating CN3 resolves the error, the root cause was likely a loose or poorly seated connector. If the error persists after confirming CN3 is secure and the wiring harness shows no visible damage, one or both control boards may have an internal fault and require testing or replacement.

Source: manufacturer service documentation.

Common causes of E91

  1. 01

    Loose or unseated CN3 connector

    Wiring / connection

    The CN3 connector linking the Main Control Board to the Display Board can work loose over time due to washer vibration. Disconnecting and firmly reseating this connector is the first step and often resolves the error entirely.

  2. 02

    Damaged wiring harness

    Part replacement

    The wiring harness running between the two boards can suffer from pinching, chafing against the cabinet, or moisture exposure, which interrupts the communication signal. Inspect the full length of the harness for cuts, fraying, or corrosion at terminal pins.

  3. 03

    Corroded or damaged connector pins

    Wiring / connection

    Even if CN3 appears seated, individual pins inside the connector can be corroded, bent, or backed out of position, preventing a reliable electrical connection. Visually inspect and clean the pins, and check for proper pin tension.

  4. 04

    Faulty User Interface Board

    Part replacement

    If the wiring and connectors check out, the UI board itself may have failed internally and is no longer sending or receiving communication signals correctly. This requires board replacement to resolve.

  5. 05

    Faulty Main Control Board

    Part replacement

    The Main Control Board can also be the source of the communication failure if it has suffered component damage or a firmware fault. This is typically diagnosed after ruling out wiring and the UI board as causes.

See the test procedure for each cause

Frequently asked questions about E91

What does E91 mean on a Frigidaire washer?
E91 indicates a communication error between the User Interface Board and the Main Control Board. These two components must exchange data continuously for the washer to operate, and E91 appears when that communication link fails. The washer stops running until the issue is identified and corrected.
Can I fix E91 on my Frigidaire washer myself?
In many cases, yes. The first step is to check connector CN3, which links the Main Control Board and the Display Board. Disconnecting and firmly reseating this connector resolves the error when a loose connection is the cause. If the error returns after reseating CN3, further diagnosis of the wiring harness and control boards is needed, which may require a technician.
Is it safe to keep using my washer when E91 is displayed?
No, the washer is designed to halt operation when E91 appears, and you should not attempt to force it through a cycle. Running a washer with a confirmed control communication fault can lead to unpredictable behavior. Address the underlying cause before resuming normal use.
Will resetting my Frigidaire washer clear the E91 error?
A reset may temporarily clear the E91 code, but if the underlying wiring or board fault is still present, the error will return during the next cycle. Resetting is useful for confirming whether the fault is intermittent, but it is not a repair. The CN3 connector and wiring harness should still be inspected even if the reset appears to work.
How much does it cost to repair a Frigidaire washer E91 error?
Repair costs vary depending on the root cause. If the fix is simply reseating the CN3 connector, there may be no parts cost involved. Wiring harness replacement typically falls in the range of $20 to $80 for parts. Replacing a User Interface Board or Main Control Board can range from $100 to $300 or more for parts alone, with additional labor costs if a technician performs the repair.

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