volume button not working when im pluged in to my cars auxiliary port

Hi Jkpeska,

Welcome to Apple Support Communities! We appreciate you reaching out for help adjusting volume while your iPhone is connected to your vehicle. Let's get to the bottom of this together.

To start, let us know which iPhone model and iOS version you're using, to ensure we're on the same page. Is the auxiliary port on your vehicle a USB port, or a 3.5 mm audio port?

Also, please confirm that this behavior is only occurring while connected to your vehicle, and that the volume buttons work as expected at all other times.

If so, next we'll confirm that you're able to hear audio while connected to your vehicle, and that you're able to adjust the volume using the controls on your car stereo. Is the maximum volume too low, or too loud?

Have a great day!