Vehicle diagnostic and troubleshooting refers to the process of identifying and resolving problems with a vehicle's various systems and components. When a vehicle's warning light or other indicator comes on, it often indicates that there is a problem with one or more of the vehicle's systems, such as the engine, transmission, brakes, or emissions.

During a diagnostic and troubleshooting process, a technician will use specialized tools and equipment to access the vehicle's onboard computer and read any diagnostic trouble codes that have been stored. These codes provide information about the specific systems or components that are experiencing problems, which can help the technician to identify the root cause of the issue.

Once the problem has been identified, the technician will then perform additional tests and inspections to further diagnose the issue and determine the most effective course of action for repairing it. This may involve replacing faulty parts, repairing damaged systems, or adjusting settings or configurations to optimize the vehicle's performance.

Effective diagnostic and troubleshooting requires a thorough understanding of vehicle systems and components, as well as the ability to interpret diagnostic codes and conduct detailed inspections and tests. It is an essential part of vehicle maintenance and repair, and can help to ensure that vehicles operate safely and reliably over the long term.