An implantable unit of a cochlear implant system is disclosed. The implantable unit includes a plurality of operational components, including a processor configured to generate electrical stimulation signals, and an electrode array configured to deliver the electrical stimulation signals to an implantee's auditory nerve. The implantable unit further includes a deactivation system configured to shut down operation of one or more of the operational components in response to the positioning of an external metallic object in proximity to the deactivation system.
