Stero Dishwasher Error Code SUMP LEVEL SENSOR: Service Required
SUMP LEVEL SENSOR with Service Required and OPEN or SHORT on a Stero dishwasher means the sump pressure switch is out of range. The machine will not operate and only allows power down. Contact your service provider; the service phone number is shown.
High: the machine will not operate until the sump level sensing is repaired.
- Code
- SUMP LEVEL SENSOR - Service Required - OPEN or SHORT
- Maker
- Stero
- Equipment
- Dish machines
- Applies to
- SU-L / SU-H undercounter (and SG glasswasher)
What does Stero SUMP LEVEL SENSOR - Service Required - OPEN mean?
The sump is the low point of the tank, and the control reads its water level through a pressure switch. If the switch reading is out of range because the circuit is open or shorted, the control no longer knows how much water is in the sump. The display shows SUMP LEVEL SENSOR, Service Required, the service phone number and OPEN or SHORT. The machine will not operate and only allows power down. Without a level reading, filling or heating could proceed blindly, so the control stops. The manual's action is to contact your service provider. The OPEN or SHORT wording tells the technician whether the switch circuit is broken or bridged, and the pressure tube that feeds the switch is also worth checking, though the manual does not list it.
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
- SUMP LEVEL SENSOR and Service Required show on the display
- The machine will not run and only allows power down
- The water level in the tank looks normal
- The service phone number is displayed
Possible causes
Likely causes — what usually sits behind SUMP LEVEL SENSOR - Service Required - OPEN on this control. A technician confirms which one it is before any part is replaced.
- A pressure switch connector loosened or corroded by the wet environment
- A pressure tube to the switch that is kinked or blocked, so the reading is out of range
Safe checks before calling for service
- Note the display text, including OPEN or SHORT.
- Look at the tank water level through the door without reaching in.
- Power the machine down and up once.
- Write down the model and message, and call us or the number on the display.
How a technician diagnoses SUMP LEVEL SENSOR - Service Required - OPEN
- Read the display and note OPEN or SHORT.
- Check the sump pressure switch wiring and connector.
- Check the pressure tube for kinks, blockage or leaks.
- Test the switch operation with the tank at known levels.
- Measure the switch circuit with a meter.
- Replace the switch or repair the wiring.
- The switch and wiring are in a wet area connected to mains power.
- Level sensing is a safety function, and the machine is locked out until it works.
- Pressure and electrical tests need the machine opened.
How SUMP LEVEL SENSOR - Service Required - OPEN differs from similar codes
SUMP LEVEL SENSOR concerns the sump pressure switch, while BOOSTER LEVEL SENSOR concerns the booster pressure switch.
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
Why does it stop the machine?
Without a level reading, the control cannot fill or heat safely.
Does OPEN or SHORT matter?
Yes, it tells the technician whether the switch circuit is broken or bridged.
Can I override it?
No. Level sensing is a protective function.
Need help with Stero SUMP LEVEL SENSOR - Service Required - OPEN?
A technician confirms the cause on site and gives you the price in writing before any work starts.