T-Mobile has rolled out May security patch update for LG G4 smartphone. With software build version H81120v, the update brings in Google security enhancements and bug fixes. The official T-Mobile page has specifically stated that the update includes a fix for e911 timer.
If you are using LG G4 handset and faced issues with e911 timer, you will not face the problem again after the installation of the update. If you inspect the software version details on the T-Mobile support page, you will notice that the update is released for Android 6.0.1 Marshmallow. However, there are reports that LG will ship Android Nougat update for the handset by the end of Q3 2017.
T-Mobile has pushed the update via OTA. Hence, it will take few days for the update to hit your smartphone depending upon the location. If you are eligible, you will receive an update message notification. Alternatively, you can verify the presence of the update by tapping Settings icon. You need to select System updates option from the About device section.
You can also verify the software version of the device by tapping Apps from the Home screen. Select Settings menu. You need to select Menu | List View if you are using Tab view. You should scroll to System and tap About phone and the option captioned Software info.
You should also establish connectivity with Wi-Fi and charge the LG G4 smartphone up to 90 percent to avoid interruption during the installation process. However, you can also make use of 4G connectivity since the update will not be heavy like a full-blown Android platform.