UniMac Washer Error Code Eio 43: Hot Fill Valve Shorted
Eio 43 on a UniMac QN washer-extractor means the I/O board found the hot fill valve shorted: the coil or its wiring draws more current than the board allows, so the board switched that output off. Close the hot water valve at the wall if you can, switch the machine off, dry any water and call us to test the valve.
High: the hot fill output has been shut off, and the cycle stops until the valve is tested.
What does UniMac error code Eio 43 mean?
Eio 43 on UniMac QN washer-extractors such as the UCA020QN means the input and output board found the hot fill valve shorted. The board watches the current it sends to each valve coil. If a coil or its wiring shorts, the current climbs past what the board allows, and the board switches the output off to protect itself. The control then stops the cycle and displays Eio 43. A valve with a shorted coil can trip the same protection again if the board is restarted, so repeated restarts achieve nothing. The code points to the hot side only. The manual lists the hot fill valve coil resistance, the valve wiring and connector, moisture at the valve, and the I/O board output stage.
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 43 on the display as soon as hot water is called for
- No hot water enters the tub
- Cold fills may still work
- Code returns after a restart
Possible causes
Listed in UniMac's documentation
- Hot fill valve coil resistance
- Valve wiring and connector
- Moisture at the valve
- I/O board output stage
Other likely causes — what usually sits behind error code Eio 43 on this control. A technician confirms which one it is before any part is replaced.
- A hot valve coil that has overheated and shorted turns after years of daily use
- Water dripping from an inlet hose onto the valve connector
- A hot-side connector crushed against the cabinet when the machine was repositioned
Safe checks before calling for service
- Write down Eio 43 and close the hot water supply valve at the wall if you can.
- Switch the machine off and keep the cabinet closed.
- Dry any water on the floor.
- Call us to test the valve.
- Tell us whether cold fills worked.
How a technician diagnoses error code Eio 43
- Read the code and confirm it appears when the hot fill is commanded.
- With power locked out, measure the hot valve coil resistance and compare it with the specification.
- Inspect the valve wiring and connector for moisture and damage.
- Swap the cold and hot valve connectors to see whether the code follows the valve.
- Replace the valve if the coil is shorted, and the board only if the valve tests good.
- The valve coil is fed from the board at machine voltage, so testing is done with the cabinet open and the supply isolated.
- A leak onto the valve connector needs to be found and fixed, or the new valve will short as well.
- Telling a shorted coil from a failed board output requires swapping and measuring.
How error code Eio 43 differs from similar codes
Eio 43 is the hot fill valve. Eio 44 is the same check on the cold fill valve.
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
Can I run cold washes while waiting?
Possibly, if the cold side works, but the code will return if the hot valve is called for.
Does a restart help?
Not if the coil is shorted. The protection trips again.
Is a leak involved?
Moisture at the valve is one of the causes the manual lists.
Need help with UniMac error code Eio 43?
A technician confirms the cause on site and gives you the price in writing before any work starts.