Abstract In new product designs increasing effort is needed to observe and prove failure mechanisms or process marginalities. For advanced failure analysis Soft Defect Localization (SDL) [1] and Time Resolved Emission (TRE) [2,3] have now become a standard analysis method. Both techniques require a close co-operation between designers and analysts. In this paper we will discuss a comprehensive study to find the mechanism behind a speed problem in the digital part of an audio signal processor. The additional delay was related to unwanted routing through poly-silicide in timing critical circuitry.