This technical report is meant to report our findings and ideas with respect to spectrum-based fault localization and modelbased diagnosis. In the following we want to introduce and compare model-based diagnosis (MBD), spectrum-based fault localization (SFL) and our contributions using 3-inverters as a running example (which is simple, yet sufficiently interesting). The remainder of this paper is organized as follows. The concepts and definitions used in this paper are given in the next section. The combination of model-based diagnosis and Bayesian reasoning, as it is normally applied to, e.g., digital circuits, is discussed in Section 3. Spectrum-based fault localization, including the system transformation for instrumentation to collect data to reason about failures is discussed in Section 4.1. In Section 4.2 we investigate several novel approaches for applying model-based diagnosis, and notably Bayesian reasoning to systems that have been prepared for spectrum-based fault localization.