Plug one end of the audio auxiliary cable to the headphone port of your iPhone. Take the other end of the cable and plug it to the auxiliary port on the car stereo. Set your car stereo to Auxiliary mode. Press the menu button on your car stereo and set it to auxiliary (AUX) mode.Plug one end of the audio auxiliary cable to the headphone port of your iPhone. Take the other end of the cable and plug it to the auxiliary port on the car stereo. Set your car stereo to Auxiliary mode. Press the menu button on your car stereo and set it to auxiliary (AUX) mode.

Why does my iPhone not connect to AUX?

Restart your iOS device and your car. Connect your iOS device to a different stereo USB port (if you have one). Try a different Lightning to USB cable. Update your iOS device.