Interposers used in 2.5D technologies introduce new challenges for Electric Fault Isolation (EFI) due to the multiple layers of silicon, metal layers, Through Silicon Vias (TSV), solder bumps and/or copper pillars making it hard for standard EFI techniques, such as thermal and optical techniques, to localize failures due to the opaqueness of these materials [1, 2, 3]. In this paper we show that shorts in 2.5D Integrated Circuits (IC) technologies can be localized accurately in x, y and z-direction using Magnetic Current Imaging (MCI) while injecting a low power current and showing that the materials used in 2.5D semiconductor manufacturing are fully transparent to magnetic fields.