What was found
AT FLIGHT LEVEL 370 FAULT LIGHT ILLUMINATED DURING APU START. FAULT LIGHT WENT OUT AFTER 3 MINUTES. ACFT GROUNDED. PERFORMED APU BITE REF AMM 49-61-00. FOUND FAULT 49-31016. PERFORMED FIM 49-30, TASK 803 INITIAL EVALUATION AND FAULT ISOLATION PROCEDURES G 1, 2, 3 AND 4. VERIFIED NO DEBRIS IN AIR INLET DUCT OR COMPRESSOR INLET, NO DEBRIS IN CHIP DETECTOR AND APU ROTATES NORMALLY. REPLACED APU INLET TEMP SENSOR IAW AMM 49-61-31. APU OPS AND BITE CHECKED GOOD.