have a 2001, 496 (unfortunately). Engine will run fine for about 20 minutes then shuts down and would'nt refire for about 15 minutes. That was a few weeks ago, now it does same thing except it will refire right away and have a steady horn alarm. No codes found. I know it can only be 5 different sensers that will cause a steady alarm. Oil senser alarm which is new, installed with no sealer to get a good grd. sea pump press. located on sea pump, shows correct psi. at idle and wot. I have not checked the three engine coolant sensers. Has anybody had this issue? Of course mercruiser says " replace senser with known good senser". I really dont want to go buy every senser and replace randomly. Also, sent PCM to Mercruiser for a test and came back OK. There comment was to check grds, all leads and connections, which I did.
