Due to ever more complex electronic systems and the frequently growing volume of data in vehicles, vehicle access for diagnostics and Electronic Control Unit (ECU) programming has to be correspondingly efficient. For this purpose, communication-based on Ethernet technology has been precise with Diagnostics over Internet Protocol (DoIP). In recent times, Ethernet-based DoIP is useful to automotive systems, and invehicle gateways have been initiated to assimilate Ethernet with usual in-vehicle networks, such as the Local Interconnect Network (LIN), Controller Area Network (CAN) and FlexRay. The preface of in-vehicle gateways and Ethernet based diagnostic protocols not only decreases the difficulty of the networks but also reduces the renew time for ECU software reprogramming while permitting the use of a range of services, together with remote diagnostics. In this work, a remote diagnostic vehicular gateway is implemented under a Real Time Operating System (RTOS) environment for an automotive system is presented.