An improved code reader for reading and displaying OBD II diagnostic codes. The code reader displays textual diagnosis descriptions corresponding to diagnostic codes. Although the code reader preferably has a display having fewer available display characters than the number of characters in the OBD II textual diagnosis descriptions, the code reader can display both an OBD II code and the textual diagnosis description corresponding to a selected OBD II code. This is accomplished using code giving the appearance that the textual diagnosis description corresponding to the selected OBD II code is either streaming on the display or scrolling on the display.