Automotive diagnostics is the process of using specialized tools and software to scan a vehicle's computer systems and pinpoint malfunctions in its components. It involves connecting a diagnostic scanner to the car's On-Board Diagnostics (OBD) port to read error codes, which helps identify the root cause of problems, such as those indicated by a "Check Engine" light. This process replaces guesswork with precise, data-driven analysis to guide repairs for a vehicle's engine, transmission, and other systems.