Although the vast majority of users report that iOS 4.1 completely solves a frustrating proximity sensor issue in which the iPhone 4 unexpectedly mutes a call, hangs up or engages FaceTime when the device is held up to the ear, some users are still experiencing the problem after the update.
A sampling of reports from Apple’s Discussion boards:
- robpom: “I was waiting for this day and then the FIRST CALL I was on – muted within minutes.”
- Brian Snyder2: “I just installed 4.1 and on my first call activated the speakerphone twice, and face dialed a bunch of random numbers. […]”
User “Michael” has posted a YouTube video that demonstrates persistence of the issue under iOS 4.1.
Bad holdover data or another issue may cause failure of the proximity sensor fix. Perform the following routines, then check for resolution to the issue.
Reset all settings. Although this will not help with an under-sensitive proximity sensor, it may help when the proximity sensor does not engage at all. It appears that the reset may restore a disengaged sensor. Navigate to Settings > General > Reset > Reset All Settings. Note that this will erase stored messages, passwords and other information.
Restore as a new phone. It appears that bad holdover data from iPhone backups can cause this problem in some cases. Restoring as a new phone will delete contacts and other data, but may resolve this issue. To do so, connect your iPhone or iPod touch to your computer, click “Restore” in iTunes, then choose “setup as new phone.”