Stero Dishwasher Error Code BOOSTER LEVEL SENSOR: Service Required
BOOSTER LEVEL SENSOR with Service Required and OPEN or SHORT on a Stero dishwasher means the booster 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 booster level sensing is repaired.
- Code
- BOOSTER 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 BOOSTER LEVEL SENSOR - Service Required - OPEN mean?
The booster is the small heated vessel that supplies the final rinse, and its water level is read through a pressure switch. When the switch reading is out of range, because its circuit is open or shorted, the display shows BOOSTER LEVEL SENSOR, Service Required, the service phone number and OPEN or SHORT. The machine will not operate and only allows power down, since a booster heater running without a trustworthy water level could overheat. The manual marks the booster temperature error as SU-H only but does not state the model for the booster level error, so we do not limit this page to one model. The manual's action is to contact your service provider. The wording OPEN or SHORT gives the technician the starting point for testing the switch circuit.
Affected models and control systems
Stero dishwashers SU-L ML-130274, SU-H ML-130273, SG-40 and SG-42. The manual does not state a model limit for the booster level message.
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
- BOOSTER LEVEL SENSOR and Service Required show on the display
- The machine will not run and only allows power down
- The final rinse does not start
- The service phone number is displayed
Possible causes
Likely causes — what usually sits behind BOOSTER LEVEL SENSOR - Service Required - OPEN on this control. A technician confirms which one it is before any part is replaced.
- A booster pressure switch connector loosened by heat and vibration
- A pressure tube to the booster switch that is kinked or blocked
Safe checks before calling for service
- Note the display text, including OPEN or SHORT.
- Power the machine down and up once.
- Do not reach into the machine or open any panel.
- Write down the model and message, and call us or the number on the display.
How a technician diagnoses BOOSTER LEVEL SENSOR - Service Required - OPEN
- Read the display and note OPEN or SHORT.
- Check the booster pressure switch wiring and connector.
- Check the pressure tube for kinks or blockage.
- Test the switch with the booster at known levels.
- Measure the switch circuit with a meter.
- Replace the switch or repair the wiring.
- The booster holds hot water and is heated by mains-powered elements.
- A booster heater running without a level reading can overheat, so the cause must be proven.
- Switch tests need the machine opened and powered down.
How BOOSTER LEVEL SENSOR - Service Required - OPEN differs from similar codes
BOOSTER LEVEL SENSOR is the booster pressure switch, while SUMP LEVEL SENSOR is the sump pressure switch. BOOSTER TEMP SENSOR is the SU-H probe message.
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 the machine stop?
Without a booster level reading, the heater could run without enough water.
Is it the same as BOOSTER TEMP SENSOR?
No. That is the temperature probe, while this is the level switch.
Can I keep washing?
No. The manual says the machine only allows power down.
Need help with Stero BOOSTER LEVEL SENSOR - Service Required - OPEN?
A technician confirms the cause on site and gives you the price in writing before any work starts.