Sub-Zero Classic BI Code 15-U-10: water check valve relay open

What 15-U-10 means

Classic Built-In refrigerators with water service, such as the BI-36UFD/S, use 15-U-10 when the water check valve relay is stuck open. This relay powers the check valve on the water line. With the relay stuck open, that valve never receives power when the board calls for it. The result is usually water that does not reach the dispenser or ice maker as expected, while cooling continues normally in both sections.

Common causes of 15-U-10

A check valve relay on the board that will not close
A loose plug between the board and the check valve
A control board needing repair

✓ One safe check you can try

1. Make sure the household water supply to the refrigerator is turned on. 2. Check that the filter is seated fully and not past its change date. 3. Reset the breaker once. 4. Note whether water flows at the dispenser and whether ice is being made.

! Why to stop there

The relay is part of the powered control board
Check valve testing involves both water and electrical connections
A new valve will not work if the relay never sends power

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

→Same appliance

Other Refrigerator codes

23Sub-Zero 600, 700 and 648PRO Code 23: Defrost overheat with no feedback 50Sub-Zero 600 and 700 Series Code 50: Refrigerator compressor running too long 41Sub-Zero 648PRO Code 41: Zone compressor or wiring problem 81Sub-Zero 700-2 Code 81: Variable-Speed compressor fails to start 82Sub-Zero 700-2 Code 82: VS compressor controller needs replacement 88Sub-Zero 700TF Code 88: Board and compressor controller not talking 80Sub-Zero 700TF Code 80: No inverter feedback after a board change ddSub-Zero 600 and 700 Series Display dd: Diagnostics switched off

15-U-1015-U-10 questions

What is the water check valve?

It is a valve on the water line of the Classic BI that the board opens through its own relay. 15-U-10 means that relay is stuck open, so the valve gets no power.

Is this a water supply problem?

Not usually. The supply can be fine while the relay fails. Checking that the household valve is open and the line is not kinked is still a sensible first step.

What warranty applies?

Our labor carries a 30-day workmanship warranty. Before we start, you get a written price. After the repair we test water flow at the dispenser and ice maker.