garmin fishfinder temp problem

[jjudge1]

I have a Garmin 240 Blue fishfinder. It has been reading high temperatures. I called Airmar (transducer manufacturer) and they walked me through the troubleshooting procedure. I checked the resistance for the current tepm, and it was correct. This now points me in the direction of the garmin unit itself. Has anyone had this problem, and is it fixable. If there is some kind of calibration steps i need to take please let me know.