Frigidaire Washer Error Code E91 — What It Means & How to Fix It

What Does This Error Mean?

E91 means your Frigidaire washer's control boards don't recognize each other. This usually happens after a board replacement with the wrong part. It can also appear after a firmware issue or a major power event.

Affected Models

Frigidaire FFTW4120SW
Frigidaire FFTW1001PW
Frigidaire Gallery FGFW4065PW
Frigidaire Classic Series

Common Causes

A replacement control board was installed that does not match the model
Firmware on one board is a different version than the other board expects
A power surge corrupted the configuration data stored in a control board
A control board was replaced but not properly programmed for the specific model
Wire harness connecting the boards is damaged, causing intermittent misreads

How to Fix It

Unplug the washer for 5 minutes and plug it back in.

Occasionally E91 is triggered by a temporary power event and clears with a reset.
If a control board was recently replaced, verify it is the exact correct part number.

Even minor variations in part numbers can cause board incompatibility and E91.
Check the wire harness between the control panel and main board for damage.

A damaged harness can cause the boards to misread each other's configuration signals.
If E91 appeared after a power surge, both boards may need inspection.

A surge can corrupt the stored configuration on either board.
Contact Frigidaire support or a certified technician for board programming or replacement.

Some boards require programming after installation — this is not typically a DIY task.

When to Call a Professional

E91 is almost always a technician-level repair. Board programming and compatibility verification requires specialized tools. Do not attempt to swap control boards without confirming the exact part number.

Frequently Asked Questions

What is the difference between E90 and E91?

E90 means the boards have lost communication entirely. E91 means the boards are communicating, but they don't recognize each other as compatible. E91 is more likely after a part replacement with the wrong board.

Can E91 be fixed without replacing a board?

Sometimes — if the error appeared after a power event, a reset may clear it. If it appeared after a board replacement, the wrong part was likely installed. In that case, the board needs to be swapped for the correct matching part.

How do I find the correct control board part number?

Check the label on the inside of the washer door or lid — it lists your model number. Use that model number to search for the exact replacement board on Frigidaire's website. You can also call Frigidaire support at 1-800-374-4432 for parts assistance.