I have now experienced the following twice almost exactly the same to the minute. 2011 5.7 horizon MPI inboard, 135hrs. Runs perfect for approximately 1hr cruising about 2100rpm. At the 1hr mark the guardian kicks in and the alarm goes off steady. I take the throttle down to idle and pop it out of gear. Put it back into gear and throttle up it repeats at about 1400rpm. If I only throttle up to 1000rpm it won’t repeat. After 10minutes cruising at 1000rpm it will allow me to throttle back up all the way to 2100rpm and past to WOT. This will last about 15min then the whole thing starts over again. There is no evidence of anything actually being wrong. Oil pressure and water temps stay steady in parameters. Visual inspection shows nothing and exhaust rises are cool. I have cleaned the sea strainer. I can’t get a code reader for 10 days and am in the middle of a vacation. Thinking it’s a sensor issue. Any thoughts on where to look understanding that I don’t have access to the obvious answer of get a code reader.
