As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED AMBER AUTO INOPERATIVE AND AIRCRAFT HAVING PRESSURIZATION ISSUES. RETURNED TO DFW WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND THE OUTFLOW VALVE ACTUATOR HAD FAULTED. REPLACED OUTFLOW VALVE ACTUATOR AND BOTH OUTFLOW/BUTTERFLY MOTORS. SYSTEM GROUND CHECKED NORMAL OPERATION.