As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTOPILOT A WILL NOT STAY ENGAGED. USED AUTOPILOT B. GROUNDED - YES. B737-900 FIM 22-11 TASK 856 PREVIOUS FLT LEG LOGGED FAULT MSG22-11189. FIM 22-12 TASK 813 DFCS AUTOPILOT TEST FAILED AND LOGGED MSG22-11134, MSG22-11122, MSG22-11125, MSG22-11126. AILERON RIGGING TEST CHECK FOUND MSG 22-11147. REMOVED AND REPLACED A/P ACTUATOR A, OP TEST PASS REF B737-900 AMM 22-11-25. DFCS LIBRARY TEST 31 ROLL SENSOR TEST PASS. LAND VERIFY TEST AMM 22-11-00-700-801 PASS.