The use of Failure Modes and Effects Analysis (FMEA) as the basis for a Diagnostic Service Tool (DST) is discussed in the context of Design for Service. Designers are assisted in developing diagnostic service tools early in the design process rather than this being a post-production activity. A system for computerised interactive FMEA generation from FMEA elements has been created by enhancing an existing object-oriented FMEA model to generate the FMEA elements and Diagnostic FMEA. The use of an object-oriented FMEA environment and FMEA object libraries promotes the reuse of information and increases data availability for diagnostic tool development. The Diagnostic Service Tool (DST) uses existing failure mode data to determine further characteristics of the failure of parts. The prototype software has been evaluated in a field service application using four automatic transmission problem cases. There was significant difference in repair times between the use of conventional repair manuals and DST. The research has demonstrated that the prototype software is successful in providing effective field service tools and suggests a method of providing feedback to the designer. In this way knowledge sharing between engineering and field service can be continuous and provide a significant improvement in product development. The approach has validity across many domains but has so far only been evaluated in the context of automotive systems and in particular automatic transmissions. Application in other areas would require substantial efforts in knowledge acquisition but the same general methods would be used.