UniMac QN Washer Error Code E LP: Low Level Pressure Switch
On UniMac QN washer-extractors with heat, E LP is the low level pressure switch error, enabled only during the Factory Test Cycle, so most owners never see it. Power the machine down and up again, then start a normal cycle. If E LP shows on a normal cycle, call us.
Low: tied to the Factory Test Cycle; a normal restart usually restores normal operation.
What does UniMac error code E LP mean?
Most owners will never see E LP, because it belongs to the Factory Test Cycle rather than to normal washing. During that test the control checks the low level pressure switch at a specific step. If the switch is in the wrong state at that step, the control shows E LP. The check is enabled only during the test cycle, so a normal wash does not use it. It is rarely a concern. The pressure switch position, the tubing to the switch and the wiring at the switch are what we look at if it does appear. The commonest explanation is that the test cycle was started by mistake, for example by a key sequence meant for something else. If E LP appears on a normal cycle, that is unexpected and worth a call. A normal restart will usually bring the machine back to normal operation.
Affected models and control systems
This applies to UniMac QN washer-extractors of 20 to 100 lb with heat, such as the UCA020QN, in the CHM1792C family. The code is enabled only during the Factory Test Cycle.
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 LP on the display during an unusual start
- Test cycle running instead of the normal program
- Code gone after a normal restart
Possible causes
Listed in UniMac's documentation
- Pressure switch position
- Tubing to the switch
- Wiring at the switch
- Whether the test cycle was started by mistake
Other likely causes — what usually sits behind error code E LP on this control. A technician confirms which one it is before any part is replaced.
- A pressure tube that has come off its fitting or kinked
- A switch whose contacts have stuck in one state
- An operator who selected the test cycle while setting up a program
Safe checks before calling for service
- Power the machine down and up again.
- Start a normal cycle and watch the first fill.
- Avoid starting the test cycle again.
- Check that the supply valves are open.
- If E LP shows on a normal cycle, call us.
How a technician diagnoses error code E LP
- Ask how the cycle was started and whether the test cycle was selected.
- Confirm the code appears only in the test cycle.
- With power locked out, inspect the tubing to the pressure switch for kinks or leaks.
- Check the switch state against water level with a meter.
- Check the switch wiring.
- Replace the switch or tube only if it fails on a normal cycle too.
- The pressure switch wiring sits near live control circuits.
- Checking the switch against the actual water level requires safe handling of water and power together.
- Switch work is not needed if the test cycle was merely started by mistake.
How error code E LP differs from similar codes
E LP belongs to the Factory Test Cycle, while E FL and E LF are normal-cycle water level codes.
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
Do I need to worry about E LP?
Usually not. It is enabled only during the Factory Test Cycle.
How did the test cycle start?
Probably a selection by mistake. Restarting with a normal program should avoid it.
What if it shows on a normal cycle?
Then the switch or its tubing may be the cause, so call us.
Need help with UniMac error code E LP?
A technician confirms the cause on site and gives you the price in writing before any work starts.