I'm working on a 170 code right now. I've swapped out a front board, back board, checked the voltages, (what the flow diag says to do) but still has code. Will be back today or tomorrow to replace sensor (my diagnosis, we'll see if im right), and will let you know then what happened.

Update: Changed the flow, temp, salinity sensor and that fixed it. Crazy, those flow sensor have turned out to be a real pain the past year or so.