UniMac Commercial Washer Error Code E Co: SCI Link Lost
E Co on a UniMac QN washer-extractor means the SCI link between the front-end control and the input and output board has broken down. Disconnect and reconnect power and let the display start. If E Co returns, the cable or a board needs checking.
High: the control cannot command the machine while the link is down, so cycles stop.
What does UniMac error code E Co mean?
The front-end control and the input and output board talk to each other over a serial link called SCI. The control sends commands, such as fill, drain or lock the door, and the board answers. If that exchange stops, the cycle cannot be commanded, so the machine stops and the display holds E Co. It is similar to other board link codes but specific to this serial connection. The most common causes are a loose or damaged SCI cable, a connector not fully seated at either end, or electrical interference picked up by the cable routing. A power cycle restarts both ends and can restore the link for a while. If the cable or a board is the real issue, the code will come back, often at random times. The display alone will not say which end has failed.
Affected models and control systems
This applies to UniMac QN washer-extractors of 20 to 100 lb, such as the UCA020QN, in the CHM1792C family with the front-end control.
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
- E Co on the display
- Cycle stopping with no clear reason
- Keys that no longer respond after the code appears
- Code returning at random times
Possible causes
Listed in UniMac's documentation
- A loose or damaged SCI cable between the front-end control and the I/O board
- A connector not fully seated at either end of the SCI link
- Electrical interference picked up by the SCI cable routing
Other likely causes — what usually sits behind error code E Co on this control. A technician confirms which one it is before any part is replaced.
- A cable rubbing against a door hinge or panel edge so the signal drops now and then
- A connector that vibration during spin has worked slightly loose
- A board that loses its link when its supply sags
Safe checks before calling for service
- Disconnect and reconnect power to the machine.
- Wait for the display to finish starting.
- Leave the cabinet closed and do not unplug cables.
- If E Co returns, call us.
- Write down any other messages shown and whether the code appeared during spin.
How a technician diagnoses error code E Co
- Ask when E Co appears and whether other messages show with it.
- With power locked out, inspect the SCI cable and its routing for pinch points and damage.
- Reseat the connectors at the control and the I/O board.
- Check the cable for continuity and see whether it picks up noise from nearby power wiring.
- Check the supply to the I/O board.
- Replace the cable or board that fails its check, then run a full cycle.
- The SCI cable runs close to power wiring, so tracing it means working near live circuits.
- Telling a cable problem from a board problem takes testing, not swapping blind.
- A link that drops only under vibration needs the machine opened up and checked while it runs.
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 E Co the same as the drive board code E d Co?
No. E Co is the link between the control and the I/O board. E d Co is the link to the drive board.
Will cycling power fix it?
It can restore the link for a while. If the cable or a connection is the issue, E Co returns.
Can cycles still run?
Not while the link is down. The control cannot send commands to the board.
Need help with UniMac error code E Co?
A technician confirms the cause on site and gives you the price in writing before any work starts.