A vehicle's onboard computer, often referred to as the engine control unit (ECU), is a crucial component that manages various functions of the vehicle. It processes data from sensors throughout the car, such as those monitoring the engine, transmission, and braking systems. This information helps optimize performance, fuel efficiency, and emissions. In addition to performance management, the onboard computer also supports diagnostic functions. It can detect issues within the vehicle and store error codes, which can be accessed by mechanics using a diagnostic tool. This capability aids in timely maintenance and repairs, ensuring the vehicle operates safely and efficiently.