Lowrance Elite 5/GPS Question

[Fishook]

I just put a Lowrance Elite 5 with GPS on the bow and run it off my Terrova Universal Sonar. So far so good with one exception. The surface water temp reading is about 20-25 degrees lower than what my console unit (Low 520C) reads. I had a Lowrance X67 upfront and it always matched the 520. Any ideas or suggestions before I have to look into sending back in or learn to live with the issue? There is a "Temp Calibration" feature but that is in tenths of a degree and, I believe, is to allow matching temps between say a Lowrance and a Hbird or Garmin, etc. It allows a max of 10 degrees which still makes me off 10-15 degrees.

[Shorelunch]

I might be off base . . . but did you select the Terrova as your transducer? Maybe that could make a difference.

[Fishook]

Where do I find/select that option on a menu? I am using the Lakemaster MN chip and I had to indicate I was using it with a Lowrance unit. I do not believe the GPS chip would have any effect on the TEMPERATURE reading - would it? You might be on to something in that the unit may have been calibrated based on the factory transducer and not for a Terrova US. If you can guide me to the appropriate menu on the Elite 5, I would appreciate it.

[Shorelunch]

I think it's under sonar, then settings, then transducer set up or selection.