As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - FLIGHT 2218 (BOI-LWS) DIVERTED TO SEA FOR MAINTENANCE DUE TO "ICE DETECT FAIL" CAUTION LIGHT ILLUMINATED IN CRUISE AFTER EXITING ICING CONDITIONS. REMOVED AND REPLACED NR 2 ICE DETECTOR PROBE IAW AMM TASKS 30-80-01-000-801 AND 30-80-00-400-801. PERFORMED OPERATIONAL TEST OF THE ICE DETECTION SYSTEM IAW 30-80-00-710-801. OPS TEST CHECKED GOOD. NO OTHER DEFECTS NOTED. RETURNED TO SERVICE.