551 Error on a Bully Dog GT Tuner

    November 12th, 2020

    What does a 551 error mean on a Bully Dog GT Tuner?

    1. Connect your device to the computer and open the sd card to view files. 

    2. Delete the files labeled GTT_TIF.GTG and TFILE0, TFILE1, TFILE2, Tfile3 if available and then return to the vehicle. 

    3. Go back through the install download, you will see code 550 once more. This is normal! Set up your tuning options.

    4. After selecting your tuning options return to your computer in order to download the tune files. 

    5. Open the Update Agent and plug your SD card into the PC. 

    6. Press start when prompted.

    7. Once the download has finished you are ready to return to the vehicle and go through the install download to install your tune.  

    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: 

    • Windows Computer with our Update Agent installed. If you do not have the Update Agent installed please Click Here to download it.
    • SD Card Reader
    • Your SD Card from your device.


    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. 



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