Samsung Galaxy S4 (SGH-I337) Firmware Overview
What is the latest SGH-I337 firmware?
I337UCUAMDL, released April 30, 2013 with Android 4.2.2. The archive holds 2 official builds across 1 region (CSC). Each one is the full stock ROM (flash file) for Odin, not an OTA patch.
Is the Samsung Galaxy S4 still getting updates?
Most likely not: there has been no new firmware since April 2013, so Android 4.2.2 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
All SGH-I337 firmware builds
How to Flash SGH-I337 Firmware
Put the Samsung Galaxy S4 into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Use HOME_CSC to keep your data, CSC for a full wipe.