As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CDU ENGINE BITE TEST FOUND SHORT TERM FAULT MESSAGE 73-20791. (PS3 SIGNALS DISAGREE) ON NR 1 ENGINE. ACFT GROUNDED. PERFORMED FIM 73-26 TASK 806, NO FAULTS DETECTED WITH EEC BITE TEST. PERFORMED WORK TASK CARD 78273000, NO FAULTS RECORDED IN RECENT OR FAULT HISTORY. NO ACTIVE FAULTS.