As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AIRCRAFT DIVERTED TO PHX DUE TO THE APU SHUTTING DOWN AUTOMATICALLY 3 TIMES. SINCE THE LEFT ENGINE IDG WAS PLACED ON MEL AND INOPERATIVE THE APU WAS REQUIRED TO BE RUN CONTINUOUSLY DURING THE FLIGHT. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT LANDED AT PHX WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE APU LOW OIL PRESSURE SWITCH PER AMM 49-94-14 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.