Electrostatic discharge (ESD) is often the cause of system-level failure or malfunction of embedded systems. The underlying faults are difficult to localize, as the information gained from the hardware-based diagnostic methods typically in use lacks sufficient detail. The alternative proposed in this paper is software instrumentation that monitors key registers and flags to detect anomalies indicative of failure. In contrast to hardware-based techniques, which use invasive probes that can alter the very phenomena being studied; the proposed approach makes use of standard peripherals such as the serial or Ethernet port to monitor and record the effect of ESD. We illustrate the use of this software instrumentation technique in conjunction with a three-dimensional ESD injection system to produce a sensitivity map that visualizes the susceptibility of various segments of an embedded system to ESD.