My screen goes blank when I try to use a phone app to make calls.
I tried to fix it using some proximity sensor apps but it can make it worse. So I have to press the power key and volume down key to go into the bootloader just restart everything so it gets back to normal.
Both my nexus 4 phones have the same problem, and a lot of other people need help with this... how do you fix the proximity sensor issue on the Nexus 4?
I found some code you can punch into the Root that fixed it for the Samsung Galaxy Note II... maybe there's something similar.
$ echo 0 > /sys/class/sensors/proximity_sensor/prox_cal
$ echo 1 > /sys/class/sensors/proximity_sensor/prox_cal