Got 3 year old Lowrance LMS-525C DF that the water temp is not reading right, last time out on the river spent a week without the boat coming out of the water, started off with a reading of low to mid 70s a believable temp , a day or so later water temp said like 82 had a hard time believing that and it sure didn't feel it but not imposable when it was near 100* air temp. the last day was there dang thing said it was 98.5*, so at that point I knew It was lying to me:?

Any Ideas of whats going on, couldn't find anything on the net on the subject made quick run threw manual didn't see anything