I had similar problem a couple of years ago, new gauge sorted it. I seem to remember a thread on here a while ago re Honda gauges, seems they are as reliable as the engines, seem to suffer from moisture, my speedo gave up the ghost last season, just rely on GPS speed now. This season non of the gauges are working, guess its a bad earth somewhere, least engines runs and trim / tilt is ok so not stopping us getting out for now, Round Anglesey Cruise this weekend