ERROR CODE EXPLAINED
Sub Zero 600 Series Refrigerator
Sub Zero 600 Series Refrigerator EC 21 Error Code
What it means
Sub-Zero identifies 600 Series error 21 as a defrost overheat condition.
Try this first
- If refrigerator temperatures are high, contact service.
- If temperatures are near normal, clean the condenser.
- Press and hold the door ajar alarm key for 15 seconds to clear the error code.
- Models prior to serial number 1810000 do not have a door ajar alarm key.
- The code can also be cleared by turning the unit OFF and then back ON.
- If the error code or Service light returns, or temperatures rise, contact Factory Certified Service.
Can I keep using it?⚠ Sub-Zero identifies 600 Series error 21 as a defrost overheat condition.
Repair usually required?⚠ Follow only the manufacturer-backed checks listed below before further repair diagnosis.
If the error keeps returning
Use the linked official Sub-Zero, Wolf, and Cove support article and contact Factory Certified Service if the issue remains.
Official source
Troubleshooting information verified against manufacturer support documentation.
View manufacturer support page →Safety note:ApplianceSignal provides general troubleshooting information. Always follow the appliance manufacturer's safety instructions and disconnect power when required.