As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTO THROTTLE DOES NOT FUNCTION. AUTO THROTTLE WILL ENGAGE ON BUT WHEN AUTO THROTTLE MOVEMENT IS COMMANDED, IT APPEARS AS THOUGH THE RT THROTTLE MOVES AND THE LT THROTTLE DOES NOT, CAUSING THE AUTO THROTTLE SWITCH TO TRIP OFF AND DISENGAGE (NON ETOPS AIRSPACE). GROUNDED. PERFORMED 10 AUTOTHROTTLE TESTS IAW AMM 22-31-00-710-801 "AUTOTHROTTLE OPERATIONAL TEST" AND AMM 22-31-00-710-802 "AUTOTHROTTLE SYSTEM TEST". NO FAULTS WERE INDICATED.