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Error code reference

Sub-Zero Refrigerator Error Code 45 1 00

Lights open circuit

Sub-Zero codesSub-Zero refrigerator codes

Lights open circuit. Main lights relay open, bulb open, or circuit open.

First step from the service manual

Repair circuit or replace bulb or control board.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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  • Step-by-step tests with expected resistance, voltage, and continuity values
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  • Verified part numbers when replacement is required
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What 45 1 00 means on a Sub-Zero refrigerator

Error code 45 1 00 on a Sub-Zero refrigerator indicates an open circuit condition in the interior lighting system. Specifically, this fault points to one of three failure points: the main lights relay has opened and is no longer passing current, one or more light bulbs or LED modules have failed in an open state, or there is a break somewhere in the wiring circuit that supplies power to the lights. The control board monitors the lighting circuit continuously, and when it detects that current is not flowing as expected through that circuit, it logs this fault code.

The main lights relay is a component on or connected to the control board that switches power to the interior lighting when the door is opened. If that relay fails in the open position, no current reaches the bulbs regardless of their condition. Alternatively, a burned-out bulb or failed LED module creates an open in the load side of the circuit. Wiring issues such as a broken wire, corroded connector, or loose terminal can also interrupt the circuit between the control board and the light fixtures.

Diagnosis should begin with a visual inspection of all interior bulbs or LED light boards for signs of failure. If bulbs appear intact, the next step is checking continuity through the wiring harness from the control board to the light fixtures. If wiring and bulbs check out, the main lights relay on the control board should be tested for proper switching operation. Depending on findings, the repair may involve replacing a bulb, repairing or replacing a wiring harness section, or replacing the control board if the relay has failed internally.

Source: manufacturer service documentation.

Common causes of 45 1 00

  1. 01

    Burned-out bulb or failed LED module

    Part replacement

    A failed bulb or LED light board creates an open circuit in the load side of the lighting system, which the control board detects as a fault. Inspect all interior light fixtures visually and test with a multimeter for continuity.

  2. 02

    Main lights relay failure on control board

    Part replacement

    The relay responsible for switching power to the interior lights can fail in the open position, cutting off current to the entire lighting circuit even if bulbs and wiring are intact. Testing the relay for proper switching behavior will confirm this failure.

  3. 03

    Open or broken wiring in lighting circuit

    Wiring / connection

    A broken wire, corroded connector, or loose terminal anywhere between the control board and the light fixtures will interrupt current flow and trigger this code. A continuity check along the wiring harness will identify the location of the break.

  4. 04

    Corroded or loose light socket connection

    Wiring / connection

    The socket or connector at the bulb or LED module can corrode or loosen over time, creating an intermittent or permanent open circuit. Inspecting and cleaning or reseating socket connections may resolve the fault.

  5. 05

    Failed control board

    Part replacement

    If the relay is integrated into the control board and cannot be replaced separately, the entire control board may need replacement to restore lighting circuit function. This is typically the last step after ruling out bulbs and wiring.

See the test procedure for each cause

Frequently asked questions about 45 1 00

What does 45 1 00 mean on a Sub-Zero refrigerator?
Error code 45 1 00 on a Sub-Zero refrigerator indicates an open circuit in the interior lighting system. The fault is caused by a failed main lights relay, a burned-out bulb or LED module, or a break in the wiring between the control board and the light fixtures. The refrigerator's control board monitors current flow through the lighting circuit and logs this code when it detects that current is not reaching the lights as expected.
Can I fix error code 45 1 00 myself, or do I need a technician?
If the cause is simply a burned-out bulb, a knowledgeable DIYer can replace it after safely disconnecting power to the unit. However, diagnosing a failed relay, tracing a wiring break, or replacing a control board requires comfort with electrical testing and access to the correct components, so a qualified appliance technician is recommended for anything beyond a basic bulb replacement.
Is it safe to keep using my Sub-Zero refrigerator while error code 45 1 00 is active?
Error code 45 1 00 is related to the lighting circuit and does not directly affect the refrigerator's cooling or food preservation functions. The unit should continue to cool normally while this fault is present. However, the underlying wiring or component issue should still be diagnosed and repaired to prevent potential further electrical problems.
How much does it cost to repair error code 45 1 00 on a Sub-Zero refrigerator?
Repair costs vary widely depending on the root cause. A simple bulb or LED module replacement may cost between $20 and $80 in parts. A wiring repair could run $100 to $300 including labor. If the control board needs replacement, parts and labor combined can range from $400 to $900 or more, depending on the specific model and service rates in your area.
Will resetting my Sub-Zero refrigerator clear error code 45 1 00?
A reset may temporarily clear the fault code from the display, but the code will return if the underlying open circuit condition has not been repaired. The control board will continue to detect the absence of current in the lighting circuit and log the fault again. A lasting repair requires identifying and correcting the actual failure point, whether that is a bulb, wiring, or the control board.

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