DTC C1604-04: ECU Hardware Error: General Description
WARNING: This page is about a different car, the 2016 Hyundai Sonata and 2015 Hyundai Sonata. However, it is still accessible from the selected car via links, so may be relevant.
The EPB is the acronym for Electric Parking Brake system. Instead of using pedal or lever, using switch can apply parking brake. Drive controls switch → switch signal to Module → Module activate actuator → parking brake Apply/Release. When EPB switch is pulled, parking brake gets Applied. When EPB switch is pushed down, parking brake is released.