UniMac Washer Error Code E Pr: Low Level Pressure Switch
E Pr on a UniMac UC-series washer-extractor is a low level pressure switch error, found after the first fill step of the production test cycle. It belongs to Design 1 models only and is mostly a test-cycle result. Cut power to clear it, confirm the water valves are open, and run a normal cycle.
Low: mostly a test-cycle result that power-cycling clears, and normal cycles are usually unaffected.
What does UniMac error code E Pr mean?
E Pr is the low level pressure switch error on UniMac UC-series washer-extractors such as the UCH020GNF. The low level pressure switch tells the control whether water in the tub has reached the lowest level. During the production test cycle, the control checks that switch after the first fill step. If the switch is in the wrong position at that moment, the control reports E Pr. This code belongs to Design 1 models only, and it is mainly a test-cycle result, so most owners see it only on a machine fresh from a test or after the control was reset. Cutting power to the washer clears the code. The manual's pointers are the switch position and the tubing, the water level at the first fill step, the wiring at the switch, and the control input for the switch. When E Pr appears on a normal cycle instead of the test cycle, the water level system needs checking.
Affected models and control systems
Listed for UniMac UC-series washer-extractors in the CHM495R family (20-100 lb), such as the UCH020GNF. The manual limits this code to Design 1 models; the machine's data plate shows the design.
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 Pr on the display after the first fill step of a test cycle
- Cycle stops at the first fill
- Water level in the tub does not match what the machine expected
Possible causes
Listed in UniMac's documentation
- Pressure switch in the wrong position or its tubing disturbed
- Water level at the first fill step not as expected
- Loose or damaged wiring at the switch
- Control input for the switch not reading correctly
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.
- The test cycle was started by mistake from the keypad on a machine that was otherwise ready for service
- Water supply valves left closed after installation, so the first fill never reached the low level
- A pressure tube slipped off the switch after the machine was moved
Safe checks before calling for service
- Cut power to the washer; this clears the code.
- Check that the water supply valves are open.
- Start a normal cycle, not the test cycle, and watch the first fill.
- If E Pr appears on a normal cycle, call us.
- Note whether anyone had been running the test cycle and the model design shown on the data plate.
How a technician diagnoses error code E Pr
- Confirm the machine is a Design 1 model and whether the test cycle was the one running.
- Verify the water supply and watch the first fill to see how the level builds.
- Inspect the pressure tubing between the tub and the low level switch for kinks, water or loose connections.
- Check the switch and its wiring with a meter against the wiring diagram.
- Check the control input for the switch, and replace the switch or tubing only after testing.
- The pressure switch and tubing sit behind panels near line-voltage wiring, which should be handled with the power locked out.
- The switch position can only be judged against the actual water level in the tub, which takes a controlled fill and a meter.
How error code E Pr differs from similar codes
E Pr applies to Design 1 UC machines only. It is a test-cycle detection, unlike the QN pressure sensor error E PS, which is about a missing level reading.
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 washer error codes
Why am I seeing a test-cycle code on my washer?
E Pr is tied to the production test cycle on Design 1 models. If someone started that cycle by accident, it can appear. A normal cycle usually clears it.
Does E Pr affect normal washing?
On a normal cycle it generally should not. If it does appear, the pressure switch or its tubing needs a check.
Which UC models can show E Pr?
Design 1 models only. The data plate on your machine tells us which design it is.
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.