“What to do when an equipment fails an EMC Test or in the field?” is a key issue. An EMI problem has three faces: the status of the equipment, the nature of the problem, and its occurrence. Conducted and radiated cases are treated separately since conducted phenomena dominate below the 10–30 MHz region, while radiation dominate above 30 MHz. Test labs statistics show that 50% of the products submitted for final compliance fail the first time, at least on one test, while an early EMC testing, with simple workbench tests during the design phase will reduce final failures to 10% or 15%. Workbench EMC measurements are simple, inexpensive, feasible early in the development phase to get a preview of product EMC performance, weaknesses, and strengths. Should early or official tests unveil unacceptable failures, we enter the troubleshooting phase. Troubleshooting emission problems is described first, taking less instrumentation (spectrum analyzers, and accessory LISNs and current probes). Investigating for susceptibility requires a re-creation of the fault, eventually using the “forced crash” approach via Fast Transients or Electrostatic Discharge (ESD) generators, and the Bulk Current Injection (BCI). The final section covers the specifics of EMC Hardening an Equipment at Customer Sites.