As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5374, STL TO DSM - DURING CLIMB IN ICING CONDITIONS THE FLIGHT CREW RECEIVED A BLD 2 LOW TEMP MESSAGE ON EICAS SHORTLY AFTER THE ANTI-ICING SYSTEM TURNED ON. THE QRH WAS FOLLOWED AND IT WAS DECIDED TO RETURN TO STL DUE TO WEATHER CONDITIONS AT THE DESTINATION AIRPORT. MAINTENANCE TROUBLESHOT THE FAULT TO A CLOGGED PNEUMATIC REGULATOR FOR THE BLEED 2 THERMOSTAT. THE REGULATOR WAS REPLACED AND THE SYSTEM OPERATED NORMALLY.