Genuine OEM Volkswagen Alternator, part number 079903023. This alternator is responsible for generating electrical power to charge the battery and run the vehicle's electrical systems while the engine is running. It is typically mounted to the engine block and driven by a belt. The alternator's precise voltage regulation ensures system stability and prevents overcharging or undercharging of the battery. Genuine OEM alternators are built to withstand engine vibrations and heat, ensuring reliable electrical output.