It appears some units of the iPhone SE, Apple's latest 4-inch iPhone, may have issues with Bluetooth audio connectivity. According to some early adopters of the handset, there is an audio issue with Bluetooth phone calls when the device is paired with a vehicle or a headset.
As documented by users on the Apple Support forum (via MacRumors), the issue does not limit itself to Bluetooth phone call audio but also extends to GPS voice navigation as well. However, music streaming using the Bluetooth connectivity seems untouched.
"I have a new iPhone SE and have so far paired it to a 2014 BMW 328i and a 2011 Kia Optima and a 2015 Kia Santa Fe. In all cases, I have terrible quality bluetooth call reception... the audio while on a phone call is extremely scratchy and distorted," posted an iPhone SE user on the Apple Support forum.
Although Apple is yet to come up with a solution or give its official word on the matter, the Bluetooth bug is said to affect almost all the iPhone SE models that are running iOS 9.3 or 9.3.1 versions. This is for the users in the US, Australia, Canada, Germany, Sweden, and UK for now. In addition, the iOS 9.3.2 beta release does not appear to solve the issue.
The iPhone SE Bluetooth audio bug is said to affect a variety of in-car infotainment systems from different carmakers, including Audi, BMW, Chevrolet, Chrysler, Dodge, Ford, GMC, Hyundai, Infiniti, Jeep, Kia, Mercedes-Benz, Nissan, Subaru, Toyota, and Volkswagen. Users say that they have tried restoring the iPhone SE, resetting network settings, un-pairing and re-pairing Bluetooth, toggling cellular data, and changing SIM cards but the bug still persists. Some users on the forum claim that support staff informed them Apple engineers are aware of the bug and are already working to resolve it.