Agreed. Check pitot tube. Happens periodically to my 2012 190 Sport. Inlet to pitot is on lower unit front edge below water line. If it looks clear and open, you can remove the small rubber tube from the front lower unit (this is the speedo line) and blow air through the lower unit to back flush the hole. Don't blow air in tube toward the speedo as you may end up plugging it good if the blockage made it that far. My blockages have always been contained to the lower unit especially after running in weedy and murky conditions
