What was found
WHILE TROUBLESHOOTING L/P 60078464, FOUND MAINTENANCE MESSAGE 49-91227 LOW OIL QTY (APU) ON THE PREVIOUS START. NO REPORTS OF BLUE MAINT LIGHT. APU OIL QTY READS FULL. GROUNDED-YES. POSSIBLE NUISANCE FAULT (ECU SW 4910-TUS-A53-00), REF B737-900 FIM 49-60 TSK 801. PERFORMED FIM 49-90 TSK 804 WITH NO DEFECTS NOTED. OIL QTY WAS APPROACHING ADD LINE, SERVICED TO FULL. APU OIL SENSOR FLOAT APPEARS SLIGHTLY STICKY. REPLACED OIL LEVEL SENSOR, PER B737-900 AMM 49-94-11. LEAK AND OPERATIONS CHECK GOOD. ETOPS GROUND VERIFICATION SUCCESSFUL.