Due to a recent cost reduction (and feature reduction) many of the cheap ELM327 OBDII Bluetooth adapters from Asia no longer work with the Leaf and report themselves to be version 2.1. The previously recommended Bluetooth Konnwei KW902 OBDII adapter is also no longer recommended as a batch of defective ones have made their way into the market. These will basically short out your Leaf's CAN bus (or any CAN bus they are plugged into). But when removed do not seem to cause any lasting damage.
With the release of version 0.39.97 LeafSpy Pro now supports two Bluetooth 4.x LE approved adapters. The recommended one is the LELink available from Amazon. Bluetooth 4.x LE has the advantage of not needing to be paired and lower power from both the Android device and the Leaf. The LELink is highly recommended and also works with the iOS version of LeafSpy Pro.
