What does a 550 error mean on a Bully Dog GT Tuner?
This means that the tune files have been selected and need to be downloaded from the Bully Dog server.
You will need:
1. Go to a Windows computer and open the Update Agent.
2. Put the SD card into the SD card reader.
3. Click on "start" in the Update Agent to download the tune(s) (this is not updating the device).
4. Return to your vehicle and select "install download" in the main menu. After the disclaimers, you will select continue with selected tunes to select tune (A, B, or C) that you want to install.