As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED ANTI-ICE DUCT RED WARNING MESSAGE 500 FEET AFTER TAKEOFF. ALL ANTI-ICE WAS OFF AT THE TIME. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, REMOVED AND REPLACED LEFT FUSELAGE SENSING ELEMENT AND PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT RELEASED FOR SERVICE.