UniMac Washer Error Code Eio 39: Mosfet Enable Will Not Turn Off
Eio 39 on a UniMac QN washer-extractor means the Mosfet enable on the I/O board cannot be disabled: the control told the board to switch its outputs off and the enable stayed on. This is more serious than Eio 38, because outputs such as a valve could stay powered. Switch the machine off at once, close the water valves if you can, and call us.
High: outputs such as a valve could stay powered when they should be off.
What does UniMac error code Eio 39 mean?
On UniMac QN washer-extractors such as the UCA020QN, Eio 39 means the Mosfet enable on the input and output board cannot be disabled. The enable is the master permission that lets the board switch its outputs. When a cycle ends or the control needs to shut things down, it tells the board to switch the outputs off. In Eio 39 the control told the board to switch its outputs off, and the enable stayed on regardless. That is more serious than Eio 38, because outputs such as a water valve could stay powered when they should be off. The cycle halts and the display keeps the code. The manual lists a failed enable circuit on the I/O board that stays switched on, a water valve or lock output that remains powered after shutoff, and a poor connector contact on the I/O board outputs.
Affected models and control systems
Listed for the CHM1792C family of UniMac QN washer-extractors (20-100 lb), with the UCA020QN as the example model, on the input and output (I/O) board.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Eio 39 on the display and the cycle halts
- Water still entering the tub after the cycle stopped
- A valve or the lock stays energized
- Hum or click from valves that should be off
Possible causes
Listed in UniMac's documentation
- Failed enable circuit on the I/O board that stays switched on
- Water valve or lock output that remains powered after shutoff
- Poor connector contact on the I/O board outputs
Other likely causes — what usually sits behind error code Eio 39 on this control. A technician confirms which one it is before any part is replaced.
- An output that welded on after switching a valve coil for years
- A fill valve staying open and filling the tub even though the control has stopped
- A connector bridging two output pins through moisture
Safe checks before calling for service
- Switch the machine off at its power control right away.
- Close the water supply valves at the wall if you can safely reach them.
- Look for water on the floor and dry it.
- Call us and tell us the code.
- Do not restart until we have looked at it.
How a technician diagnoses error code Eio 39
- Make the machine safe by isolating power and closing the supply valves.
- Check the tub and valves for water that kept entering after shutoff.
- With power locked out, inspect the output connectors and the board for moisture and burn marks.
- Test the valve and lock outputs for voltage when the enable should be off.
- Replace the I/O board after the tests confirm the enable stays on.
- An output that will not turn off can leave a valve open and flood the room, so the supply should be closed first.
- Testing for voltage when the outputs should be off means measuring live circuits.
- The fix is replacing a board, which needs the right part and a full verification of all outputs.
How error code Eio 39 differs from similar codes
Eio 39 is an enable that stays on. Eio 38 is an enable that will not turn on, and Eio 33 is the enable hardware check.
Technical reference
- Document
- Washer-Extractor Programming CHM1792C_SVG, Part No. F8641001ENR4, Error Codes Table 29 (pp. 100-107)
- Maker documentation
- UniMac owner support
- Edition
- Part No. F8641001ENR4, January 2020
- Models / control
- CHM1792C family washer-extractor (QN models, 20-100 lb) front-end control
- Section
- Error Codes, Table 29, pp. 100-108 (PDF pages equal printed pages)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related UniMac washer error codes
Is Eio 39 an emergency?
Treat it with care. If water is still entering, close the supply valves at the wall.
Can I reset it?
Cutting power stops all outputs, but the board must be checked before the machine runs.
Why is it worse than Eio 38?
Because outputs can stay powered when the control wants them off.
Need help with UniMac error code Eio 39?
A technician confirms the cause on site and gives you the price in writing before any work starts.