If as the title of your thread says you are using just the audio jack, i.e. the AUX port, you shouldn't have any problems since the iPod is doing all the work and the car is just receiving its sound output and redirecting it to the speakers.
If you're not using just the audio jack, please give more information about what cable are you using and what exactly is the error message, where it's displayed, etc.
ITs KIA Original AUDIO Cum AUX all in one for Ipod.
It works on 1st GEN ITOUCH.
I did a google search and found out others facing same problem as me. The solution given to them it supports IPOD better than ITOUCH. Another said could be IOS in ITOUCH. But I downgrade and upgrade the IOS but also cannot play.
I found a website that sell this cable that say it supports up to 3rd GEN ITOUCH. But I got 3rd and 4th GEN ITOUCH but it kept saying USB ERROR and jumps to radio.
I don't mind buying another SAME AUX/Audio jack as long as it can detect my ipod touch......Website says it support up to 3 Gen. But I look at it, its KIA Original jack, look same as the one I have....so don't know if it works.
If the cable supports iPod touch (not ITOUCH, nothing of this sort exists) until 3rd generation, and it's not working in your situation, I would try connecting another 3rd-generation iPod touch (from a friend, etc) to make sure the problem's not with your iPod.
If the cable does not support the 4th generation, I believe you're out of luck... although if it supports the iPhone 4 it should support iPod touch 4th-gen.
Well I think you have to be mores specific about your problem!
I am using a 2g ipod Touch with my official Kia/Hyundai Ipod cable and it works all right BUT when I press SHUFFLE it shows an error and kicks me to radio! so what I did in order to stop the annoying error is to press SHUFFLE and then inmediately press MENU! no error and shuffle works perfectly! that's it!!! I don't know if that helps you but I tell you I use my 2g everyday and no problemo! Oh another thing try NOT TO MOVE the cable, because one false move and it will give you the error...that's why I don't use a case for my ipod when plugged, so it won't move. hope it helps.