How do you know when the coil pack is bad on a 2001hyundai elantra?

You can determine if the coil pack is bad on a 2001 Hyundai Elantra by observing symptoms such as rough idling, misfires, decreased acceleration, or poor fuel economy. Additionally, a diagnostic trouble code (DTC) related to the ignition system may trigger the check engine light. To confirm, you can test the coil pack's resistance with a multimeter or visually inspect it for cracks and carbon tracking. If these issues are present, replacing the coil pack is recommended.