How to fix android phone proximity sensor not working during call / screen keep on during call

Many android phone users reported proximity sensor issue including Ximoni Redmi Y1,Redmi A1that phone was after some use soon it seems that during a call the phone screen light is not turning off when it was put near the ear. It seems to be very frustrating and is very irritating as it creates many problems like unknown hold the call even call disconnected.

Troubleshoot to solve the proximity sensor issue in Android phone Wipe the cache partitioning:

What is this?

The system cache partition stores temporary system data. It's supposed to allow the system to access applications more quickly and efficiently, but sometimes things get cluttered and outdated so a periodic cache clearing can help make the system run more smoothly. It is different from clearing individual app caches, and it won't lead to any loss of personal data or settings.Many companies agree and recommend doing a cache wipe after installing a system update.

How to do this?

Press the VOLUME UP + HOME + POWER buttons all at the same time and HOLD THEM DOWN. Release only the POWER button when the device vibrates. Release the other buttons when the ANDROID SYSTEM RECOVERY screen appears. Using the VOLUME DOWN / UP buttons to navigate, select WIPE CACHE PARTITION.

Sensor Covered by phone case:

Check if you have a phone case on it that covers the proximity sensor? Please Try taking off the case and see if that helps.

Make Sure you check the following setting:

Checkbox under Settings > Device > Call Settings > Turn off screen during calls "Turn on proximity sensor during calls" is checked.

Turn off Auto brightness:                    
Redmi users are able to fix the issue by changing auto brightness is turned off and then restart the redmi phone. For many users this has worked as auto brightness feature of redmi seems to create trouble for redmi phones.

Try to reset proximity sensor:

Dial *#36# to reset the proximity sensor and this may fixed the problem.  The code may change based on Android company or model. Please check.

Calibration is testing your phone's hardware and software in user mode. Go to settings -> About phone -> tap five times on kernel version -> proximity sensor.
Do a test by putting the hand over the proximity sensor, if your phone is failing the test, press calibrates button. If calibration button is greyed out, restart your phone and try again. This thing may or may not work well.

reset to factory setting or hard reset your phone:

This may seem to fix the problem for 4-5 calls, but the user has reported that the issue may reoccur again after sometimes.
Many redmi users reported proximity sensor problem .they can use above methods and can solve there proximity sensor problem.I hope this method will solve your problem who are facing proximity sensor issues.