Sub-Zero Designer/BI Code 45-1-00: Zone 1 light circuit open

What 45-1-00 means

Sub-Zero Designer models such as the DET3050CI and Classic BI built-ins like the BI-36U/S and BI-48SD/S share 45-1-00, part of the lighting group. On Designer units it reads Zone 1 open; on the BI it is the refrigerator lights open. The control tried to power the interior lights in that section and found no complete circuit, so the lights stay dark when you open the door. Cooling and ice are not affected.

Common causes of 45-1-00

Light assembly in Zone 1 (refrigerator section) open
Loose plug at the light
Broken wire in the lighting circuit

✓ One safe check you can try

1. Open the door fully and check whether any lights in that section glow. 2. Close the door slowly to see if a flicker appears at certain angles. 3. Check that the door switch is pressed when the door is shut. 4. Use a flashlight for now and schedule service when convenient.

! Why to stop there

Lighting wiring runs behind panels and trim.
LED assemblies must match the model.
The circuit needs a meter to locate the open point.

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

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 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

45-1-0045-1-00 questions

Is a dark refrigerator section serious?

Not for food safety. 45-1-00 only affects the lights in Zone 1 or the refrigerator section, and cooling continues as usual. It is a convenience repair you can schedule at a time that suits you.

Why do Designer and BI models label it differently?

Designer units number their compartments, so the refrigerator section is Zone 1. Classic BI units use the words refrigerator and freezer instead, but the code covers the same lighting circuit idea.

How do you fix it?

We test the light assembly, its plug and the wiring behind the trim to find the open point, then quote the repair in writing. The work comes with our 30-day workmanship warranty.