As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTOTHROTTLE WON'T ENGAGE. GROUNDED-YES. PERFORMED AUTOTHROTTLE BITE, PER B737-800 FIM 22-31 TASK 801. NO CURRENT FAULTS. FOUND FAULT CODE 22-31543. PERFORMED FIM 22-31 TASK 830 WITH NO FAULTS. PERFORMED AUTOTHROTTLE SYSTEM TEST, PER B737-800 AMM 22-31-00-710-802 WITH NO FAULTS.