OBDII is an american standard used for vehicles for sale in the united states. japanese cars don't have to conform to US standards for communications protocols. they may, but they don't have to.
the code reader you have is generic, which means it will only read the 40 or so P-codes specified by the SAE listed here (http://en.wikipedia.org/wiki/Table_o...#Standard_PIDs), if they read any at all (remember about OBD being an american thing)
also read here: http://tunertools.com/forums/showthread.php?t=58