Now a days, applications of wireless sensor networks (WSNs) has been increased due to its vast potential to connect the physical world to the practical world. Also, advancement in microelectronic fabrication technology reduced the cost of manufacturing convenient wireless sensor nodes and now it becomes a trend to deploy the large numbers of wireless sensors in WSNs so that to increase the quality of service (QoS). The QoS of such WSNs is mainly affected by the faulty or malfunctioning sensor nodes. Probability of sensor node failure increases if number of sensor node increases in the network. For maintaining the better QoS under failure conditions such faulty sensor node should be detected and it should be removed. In this proposed method, faulty sensor node is detected by calculating the round trip delay (RTD) time of round trip paths and comparing them with threshold value. This proposed method is tested with three sensors Nodes designed using microcontroller, sensor and ZigBee. The main server section which will display the failure sensor node is also designed using microcontroller and ZigBee
