What was found
FLT 4739 - IN CRUISE AT FL 410, CREW RECEIVED LEFT ENGINE OIL PRESSURE MESSAGE AS WELL AS LEFT ENGINE OIL PRESSURE LESS THAN 25 PSI AND 'RED' IN COLOR. CREW PROCEEDED WITH LEFT ENGINE OIL PRESSURE MESSAGE EMERGENCY CHECKLIST. WITH ADVANCEMENT OF LEFT TRUST LEVER, THERE WAS NO CHANGE IN OIL PRESSURE. CREW COMPLETED SINGLE ENGINE PROCEDURES, DECLARED AN EMERGENCY, AND REQUESTED FIRE TRUCKS AND EMERGENCY EQUIPMENT. AIRCRAFT LANDED SAFELY IN ATL. MAINTENANCE REPLACED THE LEFT ENGINE OIL PRESSURE TRANSMITTER. LEAK AND OPERATIONAL CHECK WERE GOOD AFTER GROUND RUNS. AIRCRAFT RETURNED TO SERVICE. (X)