Error code 502 means the device doesn't recognize the vehicle's stock information as a supported application.
Please double-check that the vehicle you are attempting to install on is supported by your device. You can search for supported vehicles here.
If you are receiving this error and the device you own does support your vehicle, you may need to update the GT. To install the Update Agent click here.
For further assistance please contact our technical support team with the device, vehicle, and a Windows PC with internet access available.