As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GE DIAGNOSTICS REPORTS THE #2 ENGINE TREND DATA SHOWS A SUDDEN SHIFT IN DEGT, D CORE AND DFFHPTACCV IS MOST LIKELY CAUSE OF SHIFT(#PRI: 2) ETOPS SIGNIFICANT SYSTEM CNR ISSUED. GROUNDED - YES. REPLACED HPTACCV ON THE #2 ENGING. REF B737-800 AMM 75-21-01 ACTUATOR TEST AND IDEL LK CK GOOD.