I have a Samsung Galaxy S3. If I use the Samsung Galaxy S3 diagnostics screen (#0#), and choose "Sensor", I get the following values for "ADC":
- Screen held far away: 16
- Hand about an inch away: 70
- Completely Covered by Finger: 166
So, obviously, the proximity sensor is working to some degree. However, any app I try to use seems not to notice the change in values:
- "AndroSensor" constantly reports 2 inches
- "Android Sensor Box" constantly reports 0.0cm
Also, my screen always goes blank during a call, even when the phone is not near my face. This problem is worked around by disabling that feature.
The problem persists after a factory reset.
It seems like it would be a calibration issue, but I'm not sure if there's a way to calibrate it without rooting my phone.