if you are using the GPS mount and have enabled it on menu, there are 4 situations you may encounter.
① Green speed and satellite icon: GPS enabled and working, which is totally normal.
② Red speed and white satellite icon: GPS enabled and searching for signals, it generally happens when you are in the parking lot or somewhere with poor satellites reception.
③ "NO GPS" icon and satellite icon missing: GPS not detected. if you have actually installed a GPS mount, you may need a new GPS mount.
④ Null: GPS disabled.