Default update not available, temperature and humidity sensor not working. pls help

Hey guys, i have galaxy s4 i9505. Baseband version is I9505XXUBMGA.

my device is now in 4.2.2. I want to update kitkat version. On selecting the software update, it checks and says that device is already up to date. What is the problem ?

Also i checked the hardware check and see that my temperature and humidity sensors are not working. other sensors are fine. Please help me.