Launching a new software product on the market and maximizing the profit obtained from it is already an art considering the high expectations and conflicting requirements of the software market. Product managers have to take tough decisions regarding the product life cycle like choosing the right moment for a new release, modernization or system replacement. Under these conditions they have to continually monitor the time evolution of efforts and costs required for implementing and maintaining the software product. Software tools that are able to assess these activities constitute a great value for those who need to take product management decisions. In this paper we present an approach for measuring and monitoring maintenance efforts by focusing on measurements of coding related activities. We employ data mining techniques for classifying coding related effort and present a preliminary evaluation of using this approach.