As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD INFLIGHT T1817/24JUL - OIL PRESSURE LIGHT ILLUMINATED ACCOMPANIED BY INDICATION OF QUANTITY DECREASE TO ZERO. CREW SHUT DOWN ENGINE AND RETURNED TO ORD AND LANDED WITHOUT INCIDENT. SINGLE ENGINE TIME 20 MINUTES. REPLACED NUMBER ONE ENGINE ON 23 JUL 2007 AT ORD DUE TO OIL PRESSURE BEING OUT OF LIMITS. SYSTEM GROUND CHECKED NORMAL OPERATION.