Sub-Zero error code · 15 L 00
Sub-Zero Code 15 L 00: Main Lights Relay Stuck Open
Sub-Zero code 15 L 00 means the main lights relay is stuck open with power to the lights at all times. The fix is to verify and replace the control board.
Sub-Zero code 15 L 00 means the main interior lights relay is stuck open, leaving power applied to the lights at all times per Sub-Zero. The relay is on the control board, so the repair is to verify the fault and replace the control board.
What 15 L 00 means
The main lights relay on the control board switches the cabinet lighting on and off based on door state. With the relay reported stuck open in this fault, the board cannot remove power from the lights, so they stay energized at all times. Sub-Zero directs verifying the condition and replacing the control board because the relay is integral to it.
Severity:Minor
What you'll typically see
- Interior lights stay on continuously even with the door closed
- Lights do not turn off, raising cabinet temperature slightly
- Warm or fogged interior near the light housings
- Fault code 15 L 00 stored or shown in service mode
- Reduced bulb or LED service life from constant operation
Why 15 L 00 happens
Light relays cycle constantly with every door open and close, and the contacts can weld or fail to release after years of switching. Heat from the lighting load, contact arcing, and aging board solder joints contribute. Power surges can also damage the relay.
Common causes
- Main lights relay contacts welded or stuck
- Aged or surge-damaged relay on the control board
- Degraded solder joints at the relay on the board
- Internal board fault preventing the relay from switching lights off
Parts involved in 15 L 00
- Control board — Primary fix; the main lights relay is integral to the board, so Sub-Zero specifies verify and replace board
What you can check yourself
- Power the unit off at the breaker for two minutes, then restore power to see if the code clears
- Confirm the lights truly stay on with the door fully closed and the door switch unobstructed
- Check that nothing is propping a door switch, which can mimic always-on lights
- Note the exact code and whether it returns after the power cycle
When to book a pro
The lights relay is built into the control board and cannot be replaced on its own; a technician must verify the stuck relay and replace the board.
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Frequently asked
15 L 00 FAQ
What does Sub-Zero code 15 L 00 mean?
Code 15 L 00 means the main interior lights relay on the control board is stuck open, so power stays applied to the cabinet lights at all times. The relay normally switches the lighting on when a door opens and off when it closes, but stuck open it can no longer remove power, so the lights stay lit even with the door shut.
How is 15 L 00 different from 15 L 01?
They are opposite failures of the same main lights relay. With 15 L 00 the relay is stuck so the lights stay on continuously, while 15 L 01 is the reverse, where the relay fails to deliver voltage and the lights stay dark. Both point to the control board, but 15 L 00 is the always-on case.
Before I call, how do I rule out a simple cause for 15 L 00?
Check that nothing in the cabinet is propping or holding a door light switch in, since a blocked switch can mimic always-on lights. Confirm the lights truly stay lit with the door fully closed. If they do and the code persists, the relay on the board is the cause rather than a stuck switch.
How do I reset code 15 L 00?
Turn the unit off at the breaker for about two minutes, then restore power. If it was a momentary glitch the code clears, but a welded lights relay will keep the lights on and re-log 15 L 00, confirming the board needs replacement.
Is it harmful to leave the lights on with 15 L 00?
This is a low-severity fault. The unit cools normally and the main risk is minor: constant lighting adds a little heat near the bulbs and shortens LED or bulb life, and the interior may feel slightly warm or fogged near the light housings. It is fine to use the refrigerator while you arrange a repair.
What is the fix and the cost for 15 L 00?
Because the lights relay is integral to the control board, the repair is to verify the stuck-open relay and replace the board. Our diagnostic is a flat $89, the repair carries a 365-day warranty, and you can reach us at (650) 668-1554 to schedule and get a board estimate for your model.
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