As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIAGNOSTICS REPORTS NR 1 ENGINE EGTHDM CONTINUES TO SHOW GREATER THAN EXPECTED DATA SCATTER WITH AN INCREASE IN DELTA EGT. ACFT GROUNDED. INSPECTED ALL EGT PROBES IAW 77-21-01, TABLE C. FOUND PROBE S4 OUT OF LIMITS. REMOVED AND INSTALLED NEW S4 PROBE REF 77-21-01. RECHECKED T49.5 READINGS AND ALL READINGS ARE WITHIN LIMITS.