What was found
#1 ENG CONTROL LIGHT ILLUMINATED DURING TAXI WITH ASSOCIATED MAINT LIGHT ILLUMINATION. GROUNDED - YES. INBOUND FLIGHT DECK EFFECTS DISPLAYED THE FOLLOWING FAULT MX MESSAGES: 732 451 51 W/MX MESSAGE 77-43012; FAULT CODE 732 101 51 W/MX MESSAGE 77-43022; AND FAULT CODE 732 301 51 W/ MX MESSAGE 77-43022. ALL OCCURRING ON TAXI OUT. ACCOMPLISHED IFIM FOR MSG 77-43022. FOUND #1 ENG N1 SENSOR VALUE OUT OF TOLERANCE. HARNESS BETWEEN EEC B AND SENSOR RING OUT GOOD. REMOVED AND REPLACED THE #1 ENGINE N1 SENSOR PER B737-9 AMM 77-12-01-400-801-600. OPS AND LEAK CK GOOD. GROUND VERIFICATION SUCCESSFUL PER IFIM TASK G77-12-00-810-806.