iOS 9.3.1 (build 13E238) is an official Apple over-the-air update for the iPhone 6+, released on 2016-03-31T16:55:14Z. The update package is 1.36 GB. This is a delta (partial) update that requires 8.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c2e81d54139c0adccbff36ec34e89918726059f9.zip.