hey guys, whenever i turn the volume up on my stereo in my mk5, it turns back down to half. I know the car is under warranty, but is there a known issue on this and have any of you seen a problem like this?

Do you mean it turns back down while driving? Or when you start your car again?

I know there is that adaptive volume setting that adjust the volume depending on your speed.
There is also a volume limiting setting to limit the volume when you start your car again, so that it's not blasting in your ears as loud as when you last turned off your car. Check your manual for those two settings, on mine I have to hold the Tune button to get to them.

Also from what I've read, the radio also limits the output to the speakers, so if your turning it up REALLY loud, it'll cut the bass so the speakers don't get damaged.

As mentioned above there are several possible issues here. The radio does have a programmed power on volume, this can be changed in the settings menu if you hold the scan button for several seconds. While you are in there you can adjust how aggressive the speed sensitive volume is as well. However, most likely you are talking about the third issue above which is the speaker protection. There was an issue with the radios where this protection was too aggressive and the dealer should have a flash of new firmware to fix this. If you think this is what you are experiencing then search on vwvortex to get the details of how to get this fixed by the dealer.

i will look into that
thanks

There is nothing wrong with your HU.... You were just driving with your GF in your car......

j/k... found the problem yet?