A fault code memory management apparatus comprising: an information table memory arranged to store an information table that at least serves as a fault code table including all fault codes; a memory management unit arranged to (S150, S220) store a fault code at at least two respectively different plural areas in respective plural memories, at least one of which is non-volatile, in a readable and writable manner after (a) detecting an error of a subject vehicular device and (b) finding that the detected error corresponds to a fault code in the fault code table; an error detection unit arranged to (S310 to S320; S810 to S820) detect the error of the fault code by comparing the fault codes stored at the at least two respectively different plural areas of one of the plural memories, and if the fault codes stored at the respectively different plural areas are determined not to be all matching, (S330; S830) by determining whether at least two of the not matching fault codes are matching with fault codes stored in another one of the plural memories and (S340; S840) examining how many of them are included in the fault code table; and an authentication unit arranged to (S410 to S440, S1120 to S1140) recognize whether a fault code is a genuine fault code based on a condition that the fault code stored in the at least one non-volatile memory matches the fault code included in the fault code table by comparing each of the fault codes stored in the respectively different plural areas in the respective plural memories, at least one of which is non-volatile, and the fault code included in the fault code table, and by performing an authentication of the fault code if a discrepancy of at least one of the fault codes is found when the fault codes are retrieved from the respectively different plural areas for an examination of mutual matching, wherein the information table memory is a read-only memory, contents of which are prevented from being rewritten. an information table memory arranged to store an information table that at least serves as a fault code table including all fault codes; a memory management unit arranged to (S150, S220) store a fault code at at least two respectively different plural areas in respective plural memories, at least one of which is non-volatile, in a readable and writable manner after (a) detecting an error of a subject vehicular device and (b) finding that the detected error corresponds to a fault code in the fault code table; an error detection unit arranged to (S310 to S320; S810 to S820) detect the error of the fault code by comparing the fault codes stored at the at least two respectively different plural areas of one of the plural memories, and if the fault codes stored at the respectively different plural areas are determined not to be all matching, (S330; S830) by determining whether at least two of the not matching fault codes are matching with fault codes stored in another one of the plural memories and (S340; S840) examining how many of them are included in the fault code table; and an authentication unit arranged to (S410 to S440, S1120 to S1140) recognize whether a fault code is a genuine fault code based on a condition that the fault code stored in the at least one non-volatile memory matches the fault code included in the fault code table by comparing each of the fault codes stored in the respectively different plural areas in the respective plural memories, at least one of which is non-volatile, and the fault code included in the fault code table, and by performing an authentication of the fault code if a discrepancy of at least one of the fault codes is found when the fault codes are retrieved from the respectively different plural areas for an examination of mutual matching, wherein the information table memory is a read-only memory, contents of which are prevented from being rewritten.