The method that enables a Simulink model to execute parallel computation by using GPGPU technology is introduced.The GPGPU, General-purpose computing on graphics processing units, is a technology to accelerate program by using graphic card instead of CPU computation.This method was developed to reduce the time to detect failure mode of automatic transmission’s valve body.The valve body is the major part of automatic transmission. It is extremely important to confirm the functional safety of automatic transmission in the case that any parts of valve body failed. We have developed Simulink-based valve body failure mode simulator, and made a considerable contribution for this work.However, the number of failure mode is increasing recently. Therefore, we made the simulator to compute at a high-speed using GPGPU technology.We have sharply reduced the computation time and strengthened the computing ability to support the detection for an increasing amount of failure modes. In addition, we have automated almost a whole detection process and have made the simulator easier to use and scalable from now.