There might be a feature of the Z9200 where the radio has a "courtesy" timer to continue playing for a few minutes after the car is turned off. Many modern factory radios have this same feature. If the head unit's power wiring isn't getting the expected switched and constant 12V, it might be going into this courtesy mode. Check the switched power input (red wire in Pioneer harness) to make sure it has full 12V when the car is on and that 12V continues whenever the car is on (i.e. it doesn't switch off when the car is still on). If you replaced a factory radio and tapped into the factory radio wiring, the Pioneer red and yellow power wires might not be receiving the switched and constant 12V the deck needs. The factory wiring might be providing timed or sequenced power which is confusing the head unit.