This Android tip shows you how to disable 3G on Nexus 4 and use only 2G networks as your mobile data network. It is very useful to save battery, 3G coverage is not supported. follow the instruction:
1. Open "Settings" App
2. Tap "More" to see other settings for Wireless & Networks
3. Tap "Mobile Networks"
4. Mark "Use only 2G networks" to both disable 3G and save some battery