What is the function of the car OBD interface?

[Lawrence]

OBD is the abbreviation of On-Board-Diagnostic, which translates to "On-Board Diagnostic System". This system continuously monitors the operating conditions of the engine and the working status of the exhaust after-treatment system. Once it detects a situation that may cause excessive emissions, it will immediately issue a warning. The OBD interface in cars mainly has four functions: 1. Display of engine control unit data: The OBD interface can provide various operational data of the vehicle, such as data displayed on the vehicle dashboard, various fuel consumption records, battery voltage, air-fuel ratio, throttle opening, knock count, etc.; 2. Reading fault codes: The OBD interface can be used to read fault codes, which helps in quickly diagnosing vehicle faults and reduces the time required for manual diagnosis; 3. Changing codes to enable more functions: By connecting the vehicle's CAN bus via the OBD interface data cable and adjusting the codes of various modules, many different "hidden" functions can be enabled, achieving "additional configurations"; 4. Reading and flashing ECU-TCU programs: This allows manufacturers to update the ECU control programs at any time, but it is not recommended to modify them by oneself.