What was found
CHRONIC NGS DEGRADED. HISTORY FAULTS SHOWING 47-30063 PERFORM FIM 47-31 TASK 831, IF NO FAULTS FOUND, REPLACE O2 SENSOR & PERFORM DRAIN CAP FUEL LEAK CHECK REF AMM 47-21-00-700-801 IF SMELL FOUND COMPLETE TASK & REPLACE BACK FLOW CHECK VALVES & ASM DUE TO FUEL CONTAMINATION. IF NO FUEL FOUND. AFTER REPLACING O2 SENSOR. PERFORM SYSTEM FUNCTIONAL TEST TASK 47-00-00-720-801"ALT METHOD NGS BITE DISPLAY", TO VERIFY CORRECT OPERATION & TEMP. CLOSE THIS LOG AFTER C/W.