Abstract: Wireless sensor network used Clustering techniques to extend the lifetime of the network. LEACH is the one from these clustering techniques to maintain the energy efficiency of sensors. The technique of selecting nodes with highest residual energy as cluster heads with the assumption that energy consumption distribute periodically between the nodes. Cluster heads collect information from the surrounding nodes and send it to the base station. but sometimes if one of this clusters fails it cannot be detected by the cluster heads or BS. Non cluster heads and sub cluster heads still send data to the failed CH in every time slot of a frame allocated to them, hence more energy is consumed. In this paper, we have proposed a new algorithm of fault tolerance to determine the cluster heads failures within a few seconds after the beginning of each round to enhance the lifetime of wireless sensor network.