There is a strong motivation for a node to deny packet forwarding to others and being selfish in MANET. Recently, some solutions have been proposed, but almost all of these solutions rely on the watchdog technique, which suffers from many drawbacks, particularly when using the power control technique. To overcome this problem with a moderate communication overhead, this paper introduces a new approach for detecting misbehaving nodes that drop data packets in MANET. It consists of two stages: i) the monitoring stage in which each node monitors its direct neighbours with respect to forwarding data packets of a traffic session in the network, and ii) the decision stage, in which direct neighbouring nodes decide whether the monitored node misbehaves or not. Our new approach is able to detect the misbehaviour in case of power control employment, with a low communication overhead compared to the existing approaches.