UniMac UC Washer-Extractor Error Code E Pr: Pressure Switch Position
E Pr on a UniMac UC-series washer-extractor means the low level pressure switch sat in the wrong position after the first fill step of the production test cycle. Shut the machine off and run a normal production cycle. Call us if E Pr shows up on a normal one.
Low: tied to the production test cycle, so ordinary washing is unaffected.
- Code
- E Pr
- Maker
- UniMac
- Equipment
- Industrial laundry
- Applies to
- CHM495R family washer-extractor front-end control (20-100 lb)
What does UniMac error code E Pr mean?
On a UniMac UC-series washer-extractor such as the UCH020GNF, E Pr means the low level pressure switch sat in the wrong position after the first fill step of the production test cycle. It belongs to Design 1 models only. The test cycle runs a set of checks that normal washing never does. At the end of the first fill step, the control looks at the pressure switch. If the switch is not where it should be, the control stops the test and shows the code.
Because it is tied to the test cycle, most laundries meet it only after someone selects that cycle by mistake or after the control has been reset. A low level pressure switch in the wrong position, or its tube loose, is the first cause. A water level that was not as expected at the first fill can produce it. A loose or damaged wire at the switch, or a control input that reads the switch wrongly, completes the list.
Shutting the machine off clears the display.
Affected models and control systems
E Pr is listed for the CHM495R family UC-series washer-extractors, Design 1 models only, 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
- The display shows E Pr after the first fill of the test cycle
- Normal cycles run without the code
- The code appeared after a control reset
- The fill itself looked normal
Possible causes
Listed in UniMac's documentation
- A low level pressure switch in the wrong position, or its tube loose
- A water level that was not as expected at the first fill
- A loose or damaged wire at the pressure switch
- A control input that reads the switch wrongly
Other likely causes — what usually sits behind error code E Pr on this control. A technician confirms which one it is before any part is replaced.
- Test cycle chosen from the menu after a settings reset
- Switch tube slipped off its fitting
- Supply valve closed, so the first fill never reached the level
- Switch terminal loosened by vibration
Safe checks before calling for service
- Shutting the machine off clears the code on the display.
- Look at the water supply valves and see that they are open.
- Start a normal production cycle, not the test cycle, and watch the first fill.
- If E Pr shows up on a normal cycle, call us.
How a technician diagnoses error code E Pr
- Read the code and ask which program was running.
- Confirm whether the production test cycle was selected.
- Check the tube and wiring at the pressure switch.
- Test the switch with a meter while changing the pressure.
- Replace the switch only if it fails; check the control input if it passes.
- The test cycle is a service routine and should be run by a technician.
- Testing the switch involves opening panels near live wiring.
- A wrong switch state needs a controlled fill to verify.
How error code E Pr differs from similar codes
E Pr is the Design 1 UC test-cycle pressure switch code, while E LP is the similar QN code with the Factory Test Cycle.
Technical reference
- Document
- Washer-Extractor Programming CHM495R_SVG, Part No. F8208501ENR10, March 2017, Error Codes (pp. 36-37)
- Maker documentation
- UniMac owner support
- Edition
- Part No. F8208501ENR10, March 2017
- Models / control
- CHM495R family washer-extractor front-end control (20-100 lb)
- Section
- Error Codes table, pp. 36-37 (E Pr only on Design 1 models; Ed01-Ed11 on Design 2 and 3 models)
- 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
Why do I see E Pr only sometimes?
It comes with the production test cycle, which is rarely used.
Does it apply to every UC machine?
No. It belongs to Design 1 models only.
Is the washer broken?
Probably not. Try a normal cycle and call us if it shows there.
Need help with UniMac error code E Pr?
A technician confirms the cause on site and gives you the price in writing before any work starts.