As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING ASA T/C 78273000 FOUND MAINT MSG NBR 77-20861 (THE BOTTOM LEFT EGT SIGNAL T495 S3 IS OUT OF RANGE FOR NO#1 ENGINE). GROUNDED - YES. REF B737-900 FIM TASK 77-21 TASK 803, EEC BITE TEST GOOD W/O FAULTS. WIRING CHECKED GOOD PER B737-900 AMM TASK 77-21-01-200-801-F00. REMOVED AND REPLACED #1 ENG T49.5 S3 PROBE IAW AMM 77-21-01/401. EEC BITE TEST GOOD.