Written by
Jordan Avery Appliance Repair Content SpecialistPublished August 19, 2026
Content status:
Verified
Error code50 U 86
ApplianceRefrigeration
Affected model seriesBuilt-In BI SWS #4380000
Quick answer
Water Flow meter detected low flow.
Model compatibility: Sub-Zero reused visible code strings across series and model years, so 50 U 86 may mean something different on another appliance or generation. Confirm this against your model’s documentation and record your full model number before acting.
Plain language
What this code means
Built-In BI SWS #4380000: Water Flow meter detected low flow.
Signs
Symptoms you may notice
Water dispensing may be slow or may stop completely.
The ice maker may not receive enough water for a normal fill.
The appliance may detect no flow even though a water request was made.
A restricted filter, supply line, or valve can produce similar symptoms.
Before you call
Safe checks you can make
These are simple, non-hazardous checks only. If anything is unclear, stop and contact a technician.
Confirm the household water supply is open and the accessible line is not kinked.
Check the water filter installation and replacement interval if your model uses a filter.
Stop dispensing if water leaks or flow continues when no water is requested.
If normal flow does not return, professional diagnosis is recommended.
Important safety warning. Do not remove electrical covers, test energized circuits, open the sealed refrigeration system, or replace a control board based only on the displayed code.
Please avoid
What not to attempt
Electrical measurements
Control-board access
Refrigerant or sealed-system work
Internal component testing
Get help
When to call a technician
Schedule service if the code returns after a basic reset or owner-safe check, if temperatures are moving outside the normal range, if water is leaking, or if the appliance is no longer performing its primary function. A recurring diagnostic code usually means the control is seeing the same condition again. Professional diagnosis can prevent unnecessary part replacement and can identify wiring, control, sensor, airflow, water-system, defrost, or sealed-system causes that look similar from the display alone.
Seeing this code on your Sub-Zero appliance?
Book a specialist visit for a clear estimate and approval before any repair. Independent service — not affiliated with, authorized by, sponsored by, or endorsed by Sub-Zero.
Some Sub-Zero models allow a stored code to be cleared after the underlying problem is corrected. Clearing the display does **not** repair the cause. If the code comes back, use the series-specific meaning above and arrange diagnosis.
No. A diagnostic code identifies a condition detected by the control system. Wiring, connectors, airflow, power supply, control electronics, or another component can sometimes create the same code.
That depends on temperature and the affected function. If the refrigerator is above a safe food-storage temperature, the freezer is thawing, water is leaking, or an electrical issue is suspected, stop relying on the appliance and schedule service promptly.
Sub-Zero has used several generations of electronic controls. The same visible code can be assigned differently by series, zone, or software generation, which is why model applicability is included on this page.
References
Sources & references
Sub-Zero service knowledge base
Ready to get your Sub-Zero appliance working again?
Book a repair online or call us — clear estimates, approval before any work, and a workmanship warranty on completed repairs.
