A vehicular diagnostic tool is provided for receiving vehicular diagnostic codes from a vehicle on-board computer, and translating the diagnostic codes into diagnostic descriptive data. An input port is provided for receiving vehicular diagnostic codes output from a vehicle under test. A code parser parses the received diagnostic codes into diagnostic code segments. A code translator translates diagnostic code segments into corresponding diagnostic descriptor segments. And, a combiner is provided for combining the code descriptor segments to derive composite diagnostic code descriptors, wherein the composite code descriptors being collectively representative of the received diagnostic code.