As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 339 PHX-MZT - UNSCHEDULED LANDING - CREW RECEIVED ACARS MESSAGE FOR BSCU/NOSE WHEEL STEERING PROBLEM. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO PHX. MAINTENANCE REPLACED THE NOSE LANDING GEAR LEG. VENDOR REPLACED AN OVER-SIZED BEARING PER COMPONENT MM 32-27-02.