Originally Posted by twistedriku
If it helps any mike, you can set the phone into power saving mode. It fixed the issue for my s4 that I ended up returning. (It would reach temperatures of 65°C!!!) My personal advice if you are running a custom rom and kernel, dont freak out unless the phone goes over 55°C. If it stays under 55, you just need to adjust some kernel settings and you should be fine. You can dial *#0228# and itll pull up a temperature reading menu.
Will try that as well at the moment I'm using darhstalker rom with the kernel that comes with the rom, but my wife's s4 also has the issue and hers is complete stock so it just might be defective units but thanks for the advice