With recent advances of the automotive industry, advanced systems have been integrated at in-vehicle communication. However, with the change of perception to data sharing instead of standalone systems, the susceptibility to systemic vulnerability increases. The automotive intra-communication is based on the CAN (Connected Area Network) network protocol. Many types of research have analyzed the protocol's vulnerability to various types of cyber-attacks, and its implications on vehicle systems, with emphasis on safety systems. Research has found that the communication system is not immune to various types of attacks, thus providing access to crucial functions of the vehicle. This paper explores the design and implementation of intrusion detection method in intra-vehicle communication, which aims to identify malicious CAN messages. Based on the historical traffic rate, the algorithm uses a KMP approximate string-matching. Through theoretical analysis and experiments carried out on a real CAN dataset with different attack scenarios, we received very high performance during high and medium intensity attacks. To the best of our knowledge, this work is the first study that applies the KMP approximate pattern matching to IDS for the in-vehicle network security.