Vehicle diagnostics refers to the process of using specialized tools and software to identify and analyze any issues or potential malfunctions in a vehicle's electronic and mechanical systems. It involves connecting diagnostic equipment to the vehicle's onboard computer system, accessing relevant data, and interpreting the results to pinpoint the source of the problem. Vehicle diagnostics is necessary when a vehicle exhibits unusual or persistent symptoms that may indicate a malfunction, such as strange noises, warning lights on the dashboard, decreased performance, or a sudden drop in fuel efficiency. By conducting a diagnostics test, technicians can accurately diagnose the problem and provide appropriate repairs, ensuring the vehicle's optimal performance and safety.