UniMac Washer-Extractor Error Code Eio 39: Enable Won’t Turn Off
Eio 39 means the input and output board will not let its Mosfet enable switch off, so outputs such as a fill valve could stay powered. Switch the machine off right away, close the water supply valves if you can reach them safely, and call us.
High: an output that will not switch off can keep a valve open, so power and water should be cut at once.
- Code
- Eio 39
- Maker
- UniMac
- Equipment
- Industrial laundry
- Applies to
- CHM1792C family washer-extractor (QN models, 20-100 lb) front-end control
What does UniMac error code Eio 39 mean?
The Mosfet enable on a UniMac QN washer-extractor's input and output board is the master switch for the outputs. At the end of a step or when the control wants everything off, it tells the board to switch the enable off. With Eio 39, the board was told to switch its outputs off and the enable stayed on. That is more serious than Eio 38, because outputs such as a fill valve could stay powered. Production stops there, and the display keeps the code. The manual lists the I/O board enable circuit, valve and lock outputs that stay powered, board connectors, and whether the I/O board has to be swapped. An output that cannot be turned off is a flooding concern as well as a control problem. For that reason the first steps are the opposite of waiting. Cut the main power, close the water valves at the wall if you can do it safely, and wipe up water on the floor.
Affected models and control systems
This applies to the CHM1792C family of UniMac QN washer-extractors, 20 to 100 lb, front-end control, for example the UCA020QN. Eio 39 is the stuck-on counterpart of Eio 38 among the I/O board enable codes.
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 stopped
- Water still entering the drum after the stop
- A valve humming or the lock staying powered
- Water on the floor near the machine
Possible causes
Listed in UniMac's documentation
- I/O board enable circuit
- Valve and lock outputs that stay powered
- Board connectors
- Whether the I/O board has to be swapped
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.
- A Mosfet switch on the board that has shorted closed and cannot release its outputs
- A valve driver stuck on after a surge, holding water supply open
- A harness short that feeds the valve coil directly from a supply line
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 reach them safely.
- Wipe up any water you see on the floor.
- Call us and tell us the code.
How a technician diagnoses error code Eio 39
- Read the code and ask whether water kept flowing after the stop.
- With power locked out and water shut, inspect valves, harness and connectors for a short.
- Meter the output lines from the board with the machine off to check for leakage.
- Test the enable circuit under the maker's procedure.
- Replace the I/O board and any damaged valve after the stuck output is confirmed.
- An output stuck on can flood the floor and keep mains-powered valves energized.
- Finding a short between board and valves means working with live circuits and water nearby.
- A stuck-on switch on a board cannot be separated from a wiring short without a meter.
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 industrial laundry error codes
Why close the water valves?
If a fill valve stays powered, water can keep entering the machine even after the cycle stops.
Is Eio 39 worse than Eio 38?
Yes. Eio 38 stops the outputs from turning on. Eio 39 can leave them on.
Will switching off clear it?
Switching off removes power to the outputs, but the code will return if the board's enable stays stuck.
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.