Stero Dishwasher Error Code DRAIN ERROR: Service Required
DRAIN ERROR with Service Required on a Stero dishwasher means the water level in the unit will not come up. 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 water level problem is fixed.
- Code
- DRAIN ERROR - Service Required
- Maker
- Stero
- Equipment
- Dish machines
- Applies to
- SU-L / SU-H undercounter (and SG glasswasher)
What does Stero DRAIN ERROR - Service Required mean?
The control expects the tank level to reach a set height after the drain and fill steps. When the water level in the unit will not come up, the display shows DRAIN ERROR, Service Required and the service phone number. The machine will not operate and only allows power down. The wording of the message is confusing, because the error name mentions the drain while the manual describes a level that fails to rise. The two are linked. A drain valve that stays open lets water escape as fast as it enters, so the level never comes up. The manual's action is to contact your service provider and lists no causes, so we treat the reasons below as likely only.
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
- DRAIN ERROR and Service Required show on the display
- The tank does not hold water
- The machine will not run and only allows power down
- The service phone number is displayed
Possible causes
Likely causes — what usually sits behind DRAIN ERROR - Service Required on this control. A technician confirms which one it is before any part is replaced.
- A drain valve or standpipe that stays open and lets the tank empty as it fills
- An overflow or drain plug that is not seated
Safe checks before calling for service
- Check that the drain plug or overflow tube is seated if your model has one that you can see.
- Look at the tank through the door without reaching in, noting whether water is present.
- Power the machine down and up once.
- If the message returns, write down the model and what you saw, and call us.
How a technician diagnoses DRAIN ERROR - Service Required
- Read the display and confirm DRAIN ERROR.
- Check the drain valve and its seat for debris.
- Test the drain valve operation and its drive.
- Check the level sensing that confirms the fill.
- Check for leaks at the tank and fittings.
- Repair the part that fails.
- Drain valves and level switches are wet-area parts connected to mains power.
- A leak must be located and repaired correctly to keep the water in.
- The machine is locked out until it is repaired.
How DRAIN ERROR - Service Required differs from similar codes
DRAIN ERROR describes the level not coming up, and FILL ERROR describes the fill timing out. Both stop the machine.
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 a drain error if the level is low?
A drain that stays open lets water escape as it enters, so the level never rises.
Can I run the machine?
No. The manual says it only allows power down.
Is it dangerous?
The machine locks itself out, but water on the floor should be mopped up.
Need help with Stero DRAIN ERROR - Service Required?
A technician confirms the cause on site and gives you the price in writing before any work starts.