In this study, we present an online-monitoring approach using silver nanoparticle based ink on carbon fiber reinforced plastics (CFRP). After production of CFRP plates in a prepreg autoclave process and printing conductive paths on the material, we investigate the conductive paths of printed silver nanoparticle-based ink on CFRP by light microscopy. Mechanical tests with simultaneous electrical resistance measurements demonstrate the possibility to detect particular modes of failure with samples specifically designed to promote inter-fiber failures and delaminations under bending. Delaminations can be detected and localized inside the material by electrical through-thickness measurements and resistance measurements of the conductive paths allow for surface crack detection.