Error Code EC15 on a Sub-Zero ice maker machine typically indicates an issue with the ice sensor. The ice sensor is responsible for detecting ice levels and controlling the ice-making process. Here are steps you can take to diagnose and potentially address this error:

1. Reset the Ice Maker:
   Start by resetting the ice maker. Turn off the ice maker for a few minutes and then turn it back on. Sometimes, a reset can clear minor issues.

2. Check for Obstructions:
   Inspect the ice maker’s components, including the ice sensor area, for any visible obstructions, ice buildup, or foreign objects that might be interfering with the sensor’s operation. Ensure that the ice sensor path is clear.

3. Inspect the Ice Sensor:
   If you have experience with appliance maintenance and feel comfortable doing so, you can visually inspect the ice sensor for signs of damage or loose connections. The ice sensor is typically a small component with a wire attached to it. If you find any issues, consult your Sub-Zero user manual for guidance on replacing or repairing the ice sensor.

4. Professional Assistance:
   If the EC15 error code persists after attempting the above steps or if you are uncertain about inspecting or replacing the ice sensor yourself, it’s advisable to contact a Sub-Zero service technician. They can perform a more in-depth diagnosis and replace the ice sensor or related components if necessary.