In wireless sensor networks where deployment is expected to surpass the lifetime of batteries, a major part of the operation costs is expected to be consumed by maintenance costs. It is important, therefore, to identify sources of maintenance related costs and to reduce them. In this paper we propose a maintenance model to explain sources of maintenance costs in wireless sensor networks. We also introduce the concept of maintenance awareness in such networks and describe a new technique to reduce maintenance costs. Our first experimental results shows that substantial cost reduction can be achieved.