I too had a problem with my Garmin 168 sounder, the depth sounder just stopped reading the bottom and depth, sent it back and they sent a brand new one over. Only problem was it was July/August when it crapped out leaving me with no GPS for fishing and wouldn't you know the one time I got fogged in I didn't have it!! Go figure!! Will never buy the combo unit again for that reason, also went out and put one of them see in the fog machines
Can't believe I went without one, now just need to learn to use it proper.