SubZero Refrigerator Freezer Flashing “Service” Indicator – How to fix? by KatyApplianceRepair.com 

Sub-Zero error code Flashing Service indicates
a board communication failure or repeated error condition. Below is a quick reference
and troubleshooting guide for this code.

Quick Reference

Error Code	Meaning	Severity
Flashing Service	Service indicator flashing — the control board has detected a persistent fault	High

Cause & Solution

Cause	What to Check	Fix
Repeated excessive compressor run times	Clean the condenser; verify door seals and ventilation	Clear by holding the door-ajar alarm key 15 seconds; if it returns, schedule service
Control board communication failure	Check all board-to-board cable connections	Re-seat cables; replace the control board if fault persists