There are two important problems related to the management of large parking areas, which are time for searching available lots and detecting unauthorized-parking vehicles. Nowadays, there are parking guidance systems that guide the drivers toward the available lots. As a result, the systems reduce the time for searching available lots. However, these systems do not solve the problem of unauthorized-parking vehicles. This paper presents a combination of parking guidance and authentication system that is capable to verify the legality of vehicles parked at authorized-parking lots. This system consists of detection and identification modules. In the detection module, wireless sensors such as ultrasonic and magnetometers have proven their ability in detecting vehicles. In identification module, nRF24L01 with controlling of data collision, tag address, and reception acknowledgement are used, which will act similar to an active RFID. Such system has significant implications for large institutions, by making the parking lots allocated to their staff available within the same customer parking area. The system will reduce the required manpower for managing parking areas.