Stero Dishwasher Error Code WASH TEMP SENSOR: Service Required
WASH TEMP SENSOR with Service Required and OPEN or SHORT on a Stero dishwasher means the wash temperature probe is out of range. The machine continues to run cycles. Contact your service provider; the service phone number is shown on the display.
Medium: the machine runs, but it cannot confirm wash temperature until the probe is repaired.
- Code
- WASH TEMP SENSOR - Service Required - OPEN or SHORT
- Maker
- Stero
- Equipment
- Dish machines
- Applies to
- SU-L / SU-H undercounter (and SG glasswasher)
What does Stero WASH TEMP SENSOR - Service Required - OPEN mean?
The wash tank has a probe that reports the water temperature to the control. If its reading falls outside the allowed range, because the probe or its wiring is open or shorted, the display shows WASH TEMP SENSOR, Service Required, the service phone number and OPEN or SHORT. The manual says the machine continues to run cycles, so the message does not lock you out. That makes it easy to leave until later, but a machine that cannot read its wash temperature cannot confirm that the wash water is hot enough. The manual's action is to contact your service provider. The words OPEN or SHORT tell the technician where to start, since an open reading points to a broken wire or connector, and a short points to damaged insulation or moisture.
Affected models and control systems
Stero dishwashers SU-L ML-130274, SU-H ML-130273, SG-40 and SG-42.
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
- WASH TEMP SENSOR and Service Required show on the display
- The service phone number is displayed
- The machine keeps running cycles
- Wash temperature readings look wrong or missing
Possible causes
Likely causes — what usually sits behind WASH TEMP SENSOR - Service Required - OPEN on this control. A technician confirms which one it is before any part is replaced.
- A probe plug in the wash tank area loosened by steam and vibration
- A probe lead damaged by heat or by cleaning
Safe checks before calling for service
- Note the text on the display, including OPEN or SHORT.
- Check the wash tank water temperature by hand carefully or with a thermometer.
- Do not unplug anything or open panels.
- Call the number on the display or call us, and give the model and the message.
How a technician diagnoses WASH TEMP SENSOR - Service Required - OPEN
- Read the display and note OPEN or SHORT.
- Measure the wash probe resistance and compare it with the expected values.
- Inspect the probe lead and connector.
- Check the wash heater operation in case the reading is correct.
- Compare the probe reading with a thermometer in the tank.
- Replace the probe or repair the wiring.
- The probe sits in a wet, hot area near mains-powered parts.
- Telling an open from a short needs a meter.
- Wash temperature affects cleaning, so it is checked under a running cycle.
How WASH TEMP SENSOR - Service Required - OPEN differs from similar codes
WASH TEMP SENSOR concerns the wash tank, while BOOSTER TEMP SENSOR and RINSE TEMP SENSOR concern the booster and the final rinse.
Technical reference
- Maker documentation
- Stero owner support
- Edition
- ST50406 (01/16)
- Models / control
- SU-L / SU-H undercounter (and SG glasswasher)
- Section
- Operation, DIAGNOSTIC / ERROR MESSAGES (manual p. 18)
- 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 Stero dish machine error codes
Does the machine stop on this message?
No. The manual says it continues to run cycles.
What do OPEN and SHORT mean?
OPEN means a break in the probe circuit and SHORT means the circuit is bridged.
Should I keep washing?
The machine will run, but without a wash temperature reading, service should be arranged.
Need help with Stero WASH TEMP SENSOR - Service Required - OPEN?
A technician confirms the cause on site and gives you the price in writing before any work starts.