Unfortunately, I had to fix a broken screen on a Nexus 4.
I ordered a replacement screen on Amazon for 50€.
Then I followed those instructions on YouTube.
It was quite easy... Then I turned on the phone and all was working.
After rebooting, the touch screen was working only if I put 3 fingers on it.
I did a factory reset (probably at first power up the system checks the digitizer version or revision) and it fixed the problem.
Then I tried to do a phone call and... Guess what?!?! The proximity sensor was (is still) reporting always 0 as value.
The video was not mentioning about possible issues with it.
But Google does :) ...
Tried to open the phone and test but I got nothing.
Since I cannot root (I installed an app for my bank which requires phone activation and doing it 4 times per month is quite a waste of time and money) the only option would be a dialer with proximity option or a proximity sensor overrider (or develop an app myself).
I found Proximity Screen Off Lite.
Works great as workaround for broken proximity sensor.
You can set to automatically power on (or off) the screen if proximity sensor is covered for a certain amount of time. But this would make it power on also when it placed in a bag...
Luckily, there is an option to enable it only during calls.
It made my day!