Since upgrading to Android 6.0 the proximity sensor does not notice when an already approached object is removed. An implication of this issue is the black screen while having a phone conversation leaving you unable to quit a call even when you are still in dialing process.
I already tried out the recalibration tool, aswell as cleaning the backside of the display.
Strange that this problem has been fixed for Android 5.1 but now seems to occur again.
I did not have the black screen problem with Android 5.1, so I also do not have this problem with Android 6.0. Tested by calling my voicemail.
I have the same problem. Used to have the issue with 5.1. It got reasonably solved with the calibration tool (although I had to re-calibrate from time to time and be very careful on how to hold the phone to my ear). But with the recent upgrade to 6.0 the issue is back full-force and the calibration tool no longer works.
Same problem for me. Argh!
Same here, though I was on a google hangouts call
My proximity sensor isn’t working, too. The recalibration does not work. It always fails at step 2. A sensor check app says that proximity is always 0 cm.
I have exactly the same problem. I fixed it with recalibration before the 6.0 update, but after the update it stopped working again and the calibration tool stops at the second step complaining about me not removing my finger.
Apparently I didnt clean the backside enough because after another time of cleaning my proximity sensor works just fine.
I have the same problem with my upload on android 6. It worked perfectly when I was with the 5.1, sometimes I had to check my proximity sensor, but not much. Now, with Android 6 I have reboot the proximity sensor 2 times and it is still not working. I am very annoyed
Same for me - the calibration tool fixed the freaking proximity sensor with 5.1. After upgrading to 6.0 the screen turns black again when making a call, even when there is nothing near the sensor. Only can end calls with on/off button. I can do the complete process using the calibration tool, but the black screen problem remains after reboot…
I had the same problem. Dis- and reassembling the screen made the sensor work again. It works fine now.
I also did the reassembly, but when making a call, my screen turns black and cannot use my phone during the call. I activated workaround to end call via on/off button. But I still need to wait several seconds and activate my camera to be able to use it again…
Same problem here after upgrading to Android 6. I tried to recalibrate and reassembled the display but I am also back to the workaround 
I had this problem before and as well as after the update (not again ;-)). Removing the display and cleaning the backside as well as the proximity sensor (lense pen / brush) worked fine for me.
same probelm here. i especially agree on the following part of mniemeck’s post:
“[…] Used to have the issue with 5.1. It got reasonably solved with the calibration tool (although I had to re-calibrate from time to time […] But with the recent upgrade to 6.0 the issue is back full-force and the calibration tool no longer works…”
too bad fairphone does not offer to replace the proximity sensors to get rid of this problem once and for all… i don’t want to be opening and cleaning the sensor every month or so.
Recalibrated again and seels ti work now
i have the same problem since the update!
Edit: Tried to clean the glass from inside and recalibarted but it didnt help, so im pretty sure its a software bug!
I have the same problem and fairphone app to calibrate is lost somewhere i cannot access it nor upload it as it reckons it still in my phone
I never had this problem before the upgrade (or hardly ever), but now I have the same problem listed here. So this looks like a software bug rather than a hardware thing.
The screen aLeah’s go black and unresponsive if I put it next to my ear. The only way I can end a call (unless the other person hangs up), is by taking out the battery!