One of the commonest threats that mobile ad hoc networks are vulnerable to is data packet dropping, which is caused either by malicious or selfish nodes. Most of the existing solutions to solve such misbehaviour 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 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 the decision stage, in which direct neighbouring nodes decide whether the monitored node misbehave 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.