As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLIGHT, HAD DUAL FMC FAIL (VTK) FOR ABOUT 3 MIN. PERF AND NAV DATA ALL LOST. FMC'S RECOVERED, BUT DATA DID NOT. GROUNDED - YES. RT AND LT FMC'S LOGGED A PMG FAULT LAST FLT. PERFORMED B737-800 FIM 34-61 TASK 807 AND NO FAULTS FOUND DURING BITE CK. GROUND FUNCTION TEST OF BOTH FMC'S PASSED OK FOR ETOPS SERVICE.