The working principle of the on-board diagnostic system (OBD) is to monitor the operating status of the engine and the working status of the exhaust gas aftertreatment system at any time. Once it is found that it may cause excessive emissions, it will immediately issue a warning. When the system fails, the fault light (MIL) or check engine (Check Engine) warning light is on, and the OBD system will store the fault information in the memory, which can be read in the form of fault codes through standard diagnostic instruments and diagnostic interfaces. information. According to the prompt of the fault code, the maintenance personnel can quickly and accurately determine the nature and location of the fault. The appearance design of OBD system can be bought on the market is relatively single, and simple geometric shapes are mostly used as the appearance design shape. After discussion, Zhichuang Design decided to give it a powerful and safe appearance shape according to the working principle and nature of OBD. Zhichuang Design adds some geometric elements to the front and rear surfaces to make its appearance look muscular and increase the driver's sense of trust and security.