Due to the energy consumption and the deployment of a large number of sensor nodes in a harsh environment, it is common for the nodes in wireless sensor network to become faulty and transfer inaccurate data. Failure of nodes degrades flexibility and reliability of entire network. In order to ensure the network Quality of Service(QoS), various methods have been proposed to be able to detect the faulty nodes and take action to avoid further degradation of the service. In proposed methods, the nodes should transfer sensing data with fault diagnosis data. Therefore, the total network traffic is increased. In this paper, we assume that a specific algorithm module based on majority voting for performing a fault diagnosis is applied in IEEE 802.15.4 network. We divide the interested area into several zones, then assign a different time to perform the fault diagnosis for each zone. The time can be set considering the condition of a zone. Simulation results show the algorithm can reduce not only traffic volume for fault diagnosis but also collision occurred in the network effectively.