Milnor Washer-Extractor Message CHECK PROBE: Temperature Probe

What does Milnor CHECK PROBE mean?

The E-P Plus control on Milnor H_J, V_J, X_J and MWR_ washer-extractors measures the bath temperature with a probe whose electrical resistance changes with the heat. The control converts that resistance into a temperature to run hot wash steps. CHECK PROBE appears when the resistance falls outside the specified range, so the controller cannot trust the reading. The probe itself may have failed, the leads and connections may be damaged, a lead may be shorted to ground, or the controller input for the probe may be reading wrongly. The maker's own test is that the leads read within a set range between each other and infinite to ground, and a technician measures that with a meter. For the operator, there is little to do besides letting the washer finish draining, switching it off and on once to see if the message was a one-time glitch, and leaving the wiring alone. If the message returns, the probe circuit needs a technician. Without a reliable bath temperature, hot steps may not be controlled correctly.

Affected models and control systems

This applies to Milnor washer-extractors with the E-P Plus control on the H_J, V_J, X_J and MWR_ models, such as the 30022H7J. Other Milnor controls use different probe messages.

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

• CHECK PROBE on the display
• Water heating that does not match the formula
• Hot steps that run too long or too short

Possible causes

Listed in Milnor's documentation

• Temperature probe
• Probe leads and connections
• Short to ground
• Controller input for the probe

Other likely causes — what usually sits behind CHECK PROBE on this control. A technician confirms which one it is before any part is replaced.

• Probe lead rubbed through where it exits the shell
• Moisture in the probe connector from washing near the bath
• Hot water exposure that has aged the probe over years

Safe checks before calling for service

How a technician diagnoses CHECK PROBE

1. Read the message and note the formula in use.
2. Isolate power to the control.
3. Measure probe resistance between the leads and compare with the specified range.
4. Measure each lead to ground for infinite resistance.
5. Inspect the leads and connections.
6. Test the controller input; replace the probe only after the test.

How CHECK PROBE differs from similar codes

This message is about the probe resistance, unlike level or door messages that report a switch state.

Technical reference

Document

Technical Reference - Using the E-P Plus Control on H_J, V_J, X_J and MWR_ Models, MTCJUR03 (20150225), Section 4.2 Error Messages (BICJHT01)

Edition

Published Manual Number MTCJUR03; specified/as-of date 20150225

Models / control

Milnor E-P Plus control on H_J, V_J, X_J and MWR_ washer-extractors

Section

Chapter 4 Troubleshooting - 4.2 Error Messages: 4.2.1 Error Messages at Power Up (PDF p. 80) and 4.2.2 Error Messages during Normal Operation (PDF pp. 81-82)

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.