As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT, A/P B AND A/P A WOULD NOT ENGAGE. RECYCLED F/D AND BOTH AUTOPILOTS OPERATE NORMALLY DURING CLIMB & CRUISE. GROUNDED - YES. ACCOMPLISHED B737-900 FIM TASK 22-11 TASK 856. INCLUDING BITE TEST PER B737-900 AMM TASK 22-11-00-740-806. BOTH AUTO TEST AND INTERACTIVE TEST PASSED. OK FOR SERVICE.