OBD-II, or On-Board Diagnostics II, is a standardized system used in vehicles to monitor and report on the performance of the engine and other essential components. Introduced in the mid-1990s, it allows mechanics and vehicle owners to access diagnostic information through a universal connector, making it easier to identify issues and ensure compliance with emissions regulations. The OBD-II system collects data from various sensors and modules within the vehicle, providing real-time information about engine performance, fuel efficiency, and emissions. When a problem is detected, it triggers a warning light on the dashboard and stores a diagnostic trouble code (DTC) that can be read with a compatible scanner.