Sub-Zero Designer Code 15-2-01: Zone 2 relay stuck closed

What 15-2-01 means

On current Sub-Zero Designer units such as the DET3050CI and DEC3050R, 15-2-01 reports the control-board relay that switches cooling for zone 2 as closed when it should be open. On Classic BI models like the BI-36U/S and BI-48SD/S the same code means the freezer relay is stuck closed, and later Classic software stopped showing it because line interference could trigger it. With that relay closed, cooling for the section may never switch off. Owners might notice a very cold zone 2 or freezer and frost on packages.

Common causes of 15-2-01

Electrical interference on the supply fooling the relay sense circuit
Older control software on Classic BI units
Relay contacts stuck closed on the control board

✓ One safe check you can try

1) Notice whether the unit seems to run without ever pausing. 2) Compare the zone 2 or freezer reading with your setting. 3) Unplug nearby heavy loads sharing the circuit, such as a space heater. 4) Cut power at the breaker for a minute and restore it. 5) Contact us if the code reappears.

! Why to stop there

Checking relay contacts means testing a live board.
The Classic software update needs dealer diagnostic equipment.
Cooling that never switches off works the system harder than intended.

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.

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Other Refrigerator codes

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 deSub-Zero 600 and 700 Series Display de: Diagnostics enabled 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

15-2-0115-2-01 questions

Why does my freezer get extra cold with 15-2-01?

When the relay is reported closed, cooling for that section may stay on continuously. The freezer or zone 2 keeps dropping past its setting, which can freeze items harder than normal.

Is a software update the fix on a Classic BI?

Often it helps, because later Classic software stopped showing this code when line interference was the trigger. If the relay contacts are truly stuck, the board still needs repair.

What does a visit include?

We check supply quality, test the relay and board, and update software where it applies. The price is in writing first, with our 30-day labor warranty.