As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN CRUISE FLIGHT, "VTK" DISPLAYED ON BOTH ND W/ CORRESPONDING INDICATIONS OF DUAL FMC FAILURE. WHILE RUNNING QRH, FULL FMC FUNCTION RESTORED ITSELF IN LESS THAN 1 MINUTE. WE RE-ENGAGED LNAV/VNAV + LOGGED BACK IN TO CPDLC. GROUNDED - YES. ACCOMPLISHED FMC RESET PER B737-900 FIM 34-61-TASK 807 BOTH LEFT AND RIGHT FMC BACK TO NORMAL.