As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - ON FLIGHT 4172, IN ICING CONDITIONS WITH WING AND COWL ANTI-ICE ON, RECEIVED AN "ANTI-ICE DUCT" WARNING MESSAGE. USING CHECKLIST TURNED USING WING ON TWICE MORE DURING APPOACH AND RECEIVED "L" WING ANTI-ICE AND A WING ANTI-ICE MESSAGE. MAINTENANCE REMOVED AND REPLACED THE ANTI-ICE LEAK CONTROLLER. OPERATIONAL CHECK GOOD. REPLACED AS PRECAUTIONARY MEASURE. AIRCRAFT RETURNED TO SERVICE.