As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GE DIAGNOSTICS REPORTS #1 ENGINE TREND DATA SHOWS A DELTA EGT INCREASE AND EGT HOT DAY MARGIN DECREASE. EGT INDICATION ERRORS ARE SUSPECTED. GROUNDED - YES. PERFORMED B737-900 FIM 77-05 TASK 801. HAVE ECONOMIC FAULT 77-10841 TOP RH EGT T49581. PERFORMED PROBE INSPECT. REF B737-900 AMM TASK 77-21-01 AND CLEANING AMM 77-21-00. PRE S1 62.35 AND S4 80.53 POST S1 451.71 AND S4 458.59.