UniMac Washer Error Code Eio 37: Door Lock Full Hardware Check
Eio 37 on a UniMac QN washer-extractor means the I/O board failed its complete hardware check of the door lock solenoid, covering the pin, the pulse and the output together. The control stops the cycle. Write down what the door did, shut the washer down, never force the door, and call us.
High: the lock output failed its full test, so the cycle stops until it is serviced.
What does UniMac error code Eio 37 mean?
A UniMac QN washer-extractor such as the UCA020QN shows Eio 37 when the input and output board fails its complete hardware check of the door lock solenoid. Other Eio codes name one part of the lock circuit, such as the pin or the pulse. Eio 37 is the overall result: the board tested the whole lock output path and it did not pass. That covers the pin, the pulse and the output together, so the failure may sit in any of them or in the supply that feeds them. The control stops the cycle and holds the code, because the board cannot say that the lock is under control. The board needs a test. The manual lists a failed lock output path on the I/O board that fails the full test, a shorted or open coil or harness in the lock circuit, and an unstable power supply feeding the I/O board.
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 37 on the display and the cycle stops
- Lock does not latch or release as expected
- Other board codes may come before it
- Code returns after power-up
Possible causes
Listed in UniMac's documentation
- Failed lock output path on the I/O board that fails the full test
- Shorted or open coil or harness in the lock circuit
- Unstable power supply feeding the I/O board
Other likely causes — what usually sits behind error code Eio 37 on this control. A technician confirms which one it is before any part is replaced.
- A lock coil that opened after heat from many back-to-back cycles
- Supply voltage to the board that sags when the lock energizes
- A damaged harness where it passes the door hinge
Safe checks before calling for service
- Write down Eio 37 and what the door did.
- Shut the washer down and let the drum come to rest.
- Never force the door.
- Phone us with the code and the model.
- Keep the area dry.
How a technician diagnoses error code Eio 37
- Read the code and any earlier Eio codes in the history.
- Measure the board's supply voltage while the lock is commanded.
- With power locked out, test the coil and harness for open or shorted conditions.
- Check each lock output (pin, pulse, output) against the diagram.
- Replace the failed lock, harness or board after the tests.
- Several parts of the lock circuit can cause the same result, which takes systematic measurement to sort out.
- Supply checks to the board involve live control power inside the cabinet.
- Forcing the door to see whether the lock holds can injure the operator.
How error code Eio 37 differs from similar codes
Eio 37 is the full lock check. Eio 30, 31 and 32 name single pins, and Eio 34, 35 and 36 name the hardware behind them.
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
Why does the board show Eio 37 and not a pin code?
The full test covers pin, pulse and output, so it reports the overall failure.
Is the lock coil always the cause?
No. The board, the harness or the board's supply can also cause it.
Can I use the machine until the visit?
No. Keep it off until the lock circuit has been tested.
Need help with UniMac error code Eio 37?
A technician confirms the cause on site and gives you the price in writing before any work starts.