An OBD-II scanner is a diagnostic tool used to read data from a vehicle's onboard diagnostics system. This system monitors the performance of the engine and other essential components, helping to identify issues that may affect vehicle performance or emissions. The scanner connects to the vehicle's OBD-II port, usually located under the dashboard, to retrieve error codes and real-time data. Using an OBD-II scanner can help car owners and mechanics diagnose problems quickly and efficiently. By interpreting the codes generated by the vehicle, users can determine the necessary repairs or maintenance needed to keep the vehicle running smoothly and in compliance with emission standards.