The installation of an ignition interlock device is mandatory for repeat offense and extreme DUI convictions in Arizona. To start your car you must blow into the device. If the ignition interlock device registers alcohol on your breath, your lights will flash, your horn will honk and your car will not start. Many models require you to hum while blowing so that the machine can determine if someone else is blowing into the device. In this scenario, the machine will not work and your car will car will not start.