Thankyou so much for the reply.
Serial number is OW695990
Yes correct I changed temp sensor/ switch not the gauge sensor. The temp gauge reads 162, 163 when warmed up.
I have twin inner cooled 8.1 Merc with V-drive on a 2008 Searay 340 Sundancer. The boat goes into guardian mode after it reaches normal temp (163) at idle rpm (670 rpm). After stopping the engine the alarm continues to sound, the alarm sometimes will sound when the engine is not running showing...