As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AVIONIC SMOKE MASTER WARNING AND WARNING LIGHT (CWP) ILLUMINATED IN FLIGHT, NO INDICATION OF FIRE, SMOKE OR HEAT. AIRCRAFT RETURNED TO DTW. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE CLEANED AVIONIC RACK SMOKE DETECTOR PER SF340A MM. ALL CHECKS GOOD.