1. Open the Calculator App on your mobile
2. Now Enter : .12345+= on your calculator .
3. You will find SMMI Test Menu which will have all the sensors test.
4. Select Single Test Option .
5. Now Select Proximity Sensor .
If you are using any screenguard , it recommended to remove it before testing , Atleast remove the screenguard on the top part of the mobile where the speakers and Front camera are located .
6. Click On Start to run the test .
7. Now Move your Hands closer , Away and again Nearer to the Sensor[Top Part]
8. Check if the test show positive reports .
9. If you have got : " The Proximity Test Is Working Well " , then it is surely having issue with the screenguard , You should replace with a good screen protecter .
Note : The Proximity Sensor expects no obstacles to be placed in front within a range of 6 cms . So Even Transparent Screen Guard Will also stop the proximity sensor from working !
Hope , You will be able to find the issue and fix it by replacing your screenguard or your mobile phone . In most cases its the problem of the screen guard . You can search for Asus Tampered Glass Protector For Asus Zenfone 2 Laser On Ebay Or Flipkart Or Amazon , and get one for yourself .