As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIAGNOSTICS REPORTED NR 1 ENGINE TREND DATA SHOWED A SHIFT IN DELTA CRUISE AND TAKEOFF MARGIN INDICATIVE OF EGT INDICATION ERRORS. ACFT GROUNDED. T49.5 S2 PROBE HIGH RESISTANCE. REPLACED S2 PROBE IAW MM 77-21-01, EEC TEST PASS. EGT SYS INSPECTION NORMAL REF MM 77-21-01-200-801. INPUT MONITORING SHOWS S1, S4 AND S2, S3 PAIRS WITHIN 5 DEGREES.