UniMac Washer Error Code Eio 33: I/O Board Mosfet Hardware
Eio 33 on a UniMac QN washer-extractor is an I/O board hardware code saying the Mosfet enable hardware itself failed its check. The control halts the cycle, and cycles will not start. Note the cycle stage, switch the machine off, dry any water around it, and call us with the code.
High: cycles will not start until the I/O board is serviced.
What does UniMac error code Eio 33 mean?
Eio 33 on UniMac QN washer-extractors such as the UCA020QN is an I/O board hardware code for the Mosfet enable hardware. Where Eio 29 is about the pin, Eio 33 says the enable hardware itself failed its check. The Mosfets are the electronic switches that power outputs on the board, and the enable hardware is what allows them to switch. With that switching hardware in doubt, the board cannot be trusted with its outputs, and the control halts the cycle. Cycles will not start until the board is serviced, and a restart does not change that. The code comes from the board checking itself, not from the door or the valves. The manual lists the I/O board power and ground connections, connector wear or corrosion, moisture on or near the board, and the I/O board itself.
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 33 on the display and no cycle starts
- Valves and lock do not respond
- Same code after power-up
- Water or damp around the base of the washer
Possible causes
Listed in UniMac's documentation
- I/O board power and ground connections
- Connector wear or corrosion
- Moisture on or near the board
- I/O board itself
Other likely causes — what usually sits behind error code Eio 33 on this control. A technician confirms which one it is before any part is replaced.
- A ground lead to the board with a corroded lug
- Floor water wicking into the lower cabinet after a drain overflow
- Vibration cracking a solder joint on the board near the connectors
Safe checks before calling for service
- Note the code Eio 33 and the stage of the cycle.
- Switch the machine off at its power control.
- Check the floor around the washer for water and dry it.
- Call us and give us the code.
- Do not spray or wipe inside the cabinet.
How a technician diagnoses error code Eio 33
- Read the code and its history.
- With power locked out, inspect the board's power and ground connections and connectors.
- Look for moisture, corrosion and burn marks on the board.
- Measure the board supply voltage and ground continuity.
- Replace the I/O board if power and connections are good and the code returns.
- The board's power and ground connections carry the machine's control power, and measuring them is done with the cabinet open.
- Moisture damage on the board can be hard to see and needs a careful look with the power off.
- Replacing a board needs the right part and a full test cycle afterward.
How error code Eio 33 differs from similar codes
Eio 33 is the Mosfet enable hardware. Eio 29 is the enable pin, and Eio 34 and 35 concern the door lock disable and output hardware.
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
What is the difference between Eio 29 and Eio 33?
Eio 29 is the enable pin; Eio 33 is the enable hardware itself.
Can I run the washer?
No. Cycles will not start while the board is in doubt.
Could water be the cause?
Yes. The manual lists moisture on or near the board.
Need help with UniMac error code Eio 33?
A technician confirms the cause on site and gives you the price in writing before any work starts.