As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FL 320, SUDDEN LOSS OF LNAV /VNAV F/O SCRATCHPAD SHOWED SINGLE FMC ACCOMPANIED BRIEFLY VTK & MAP ON NAV DISPLAY REENGAGED LNAV/VNAV ON THE MCP. REENGAGED SUCCESSFULLY WITH NO FURTHER ANOMALIES. GROUNDED - YES. VERIFIED L/H FMC HAD NUISANCE ERROR. REF B737-900 AMM 34-61-00-860-801 FOR VTK/ MAP - OPS RESTORED. FMC L/H BITE TEST OK.