UniMac Washer-Extractor Error Code Eio 29: Mosfet Enable Pin
Eio 29 comes from the hardware self-check of the input and output board: the board's Mosfet enable pin failed. The control ends the cycle and holds the code, so switch the machine off, check for water on the floor, and call us.
Medium: the cycle ends and the code is held until the board is checked, but no door lock hazard is reported.
- Code
- Eio 29
- 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 29 mean?
The control on a UniMac QN washer-extractor runs a self-check on its input and output board, which switches outputs such as the valves and the door lock. A Mosfet is the electronic switch behind those outputs, and it has an enable pin that must answer correctly before any output is powered. Eio 29 says that pin failed its self-check. If the enable does not answer correctly, the board cannot switch those outputs safely, so the control ends the cycle and holds the code. This is a board-level hardware message, not something caused by the load or detergent. The manual points to the board connectors and the supply feeding the board, the harness condition at the board, moisture or corrosion on the board, and the I/O board itself if the code returns. Damp near the board is a practical reason to look at the floor first. The operator's job is to record the code and the cycle stage and tag the machine out of service.
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 codes are the I/O board hardware self-check group in the programming manual's error table.
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 29 on the display and the cycle ended
- No water fill or door movement after the stop
- Code returning after power-up
- Damp floor near the machine
Possible causes
Listed in UniMac's documentation
- I/O board connectors and the supply feeding the board
- Harness condition at the board
- Moisture or corrosion on the board
- The I/O board itself if the code returns
Other likely causes — what usually sits behind error code Eio 29 on this control. A technician confirms which one it is before any part is replaced.
- A water leak from a hose or valve that dripped onto the board area
- A connector that has loosened from vibration so the enable signal drops out
- A power supply voltage to the board that sags and causes the check to fail
Safe checks before calling for service
- Write down the full code, Eio 29, and the stage of the cycle when it appeared.
- Switch the machine off at its power control and leave the cabinet shut.
- Check the floor for water, since damp near the board can cause board errors.
- Ring us with the code and the model, and tag the washer out of service meanwhile.
How a technician diagnoses error code Eio 29
- Read the code and note the cycle stage at which the check failed.
- With power locked out, inspect the I/O board connectors and harness for corrosion or looseness.
- Check the board supply and ground with a meter.
- Look for moisture or leaks above and near the board.
- Replace the I/O board only after supply and connections are verified.
- The I/O board switches mains-powered valves and the door lock, so testing it means working near live circuits.
- Moisture damage must be traced to its source before a new board is fitted.
- A self-check failure can only be confirmed with the machine's service tools.
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
Is Eio 29 a load problem?
No. It is a hardware self-check on the I/O board, so changing the load or detergent will not help.
Can I power it off and on?
You may try once from the outside, but if the code returns, leave it off and call us.
What is the difference between Eio 29 and Eio 33?
Eio 33 is the matching check of the Mosfet enable hardware itself, while Eio 29 is the pin.
Need help with UniMac error code Eio 29?
A technician confirms the cause on site and gives you the price in writing before any work starts.