UniMac Washer-Extractor Error Code Eio 43: Hot Fill Valve Shorted
Eio 43 means the input and output board found the hot fill valve shorted, so it shut that output off and the control stopped the cycle. Close the hot water supply valve if you can, switch the machine off, and call us.
High: a shorted valve coil stops the cycle and can stress the board if the machine is restarted.
- Code
- Eio 43
- 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 43 mean?
The hot fill valve on a UniMac QN washer-extractor is an electric coil that the input and output board switches on to let hot water into the tub. The board monitors the current it sends. If a coil or its wiring draws far more current than the board allows, the board decides the valve is shorted, turns that output off to protect itself, and the control stops the cycle with Eio 43. A valve with a shorted coil can trip the protection again if the board is restarted, so repeated restarts do not help. 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. A leak at or above the valve can wet the connector and cause the short. The most useful operator actions are to close the hot water supply valve at the wall, keep the cabinet shut, dry the floor and call for a valve test.
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 43 is the hot side of the fill valve short 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 43 on the display and the cycle stopped
- No hot water entering the tub
- Cold fills that still work
- Damp around the valve connector
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 from hot water supply temperature and shorted internally
- A valve connector corroded by steam or a slow drip
- A hot-water hose weeping at the valve inlet onto the coil
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 shut.
- Dry any water on the floor.
- Call us to test the valve.
How a technician diagnoses error code Eio 43
- Read the code and check whether the cold valve fills normally.
- With power locked out and water shut, inspect the hot valve connector and wiring.
- Measure the hot valve coil resistance against the specification.
- Look for water at the valve and trace any leak.
- Replace the valve or connector, and test the board output afterward.
- A shorted coil in a mains-powered valve carries live voltage and is wet-area work.
- Testing the board output under load can damage it if the valve is still shorted.
- Water supply shutoffs and valve replacement involve hot water and pressure.
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
Will the cold fill still work?
Probably. Eio 43 involves only the hot valve output.
Why not restart until it works?
A shorted coil can trip the protection each time and can stress the board.
Is Eio 44 the same?
Eio 44 is the same check on the cold fill valve.
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.