As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AP A WILL NOT ENGAGE AND A+B WILL ONLY ENGAGE FOR 10 SEC. GROUNDED - YES. PERFORMED DFCS BITE REF B737-800 FIM 22-11 TASK 801. FOUND FAULTS 22-11127,22-11535. REF FIM 2213 TASK 806 REQUIRES REPLACEMENT OF PRESSURE SWITCH S771. REMOVED AND REPLACED HYDRAULIC PRESSURE SWITCH REF B737-800 AMM 22-11-40-400-801. COMPLETED OPS TEST FROM STEP H REF AMM 22-11-40-400-801. ALL TEST PASS.