2018 Yamaha FX Cruiser

I bought this 2018 Cruiser with 12 hours on it but I’ve had this continued issue. The ski runs great for about 1 1/2 hours and then all of sudden the check engine and temperature light comes. No water circulation issues or clogging from the intake. The ski goes into limp mode (which it should). If you turn off the motor for a few minutes the cooling temperature goes away but the check engine light remains and the motor will stay in limp mode for couple of minutes and the ski will resume at regular throttle and speed. Took it to a repair shop (TWICE), first time he couldn’t replicate the issue but the YPIS indicated a 252 error code (Engine Overheat), next visit he replace the engine sensor. The repair shop also indicated the engine has NEVER gotten to 220 degrees to cause an error code. We bought the OEM manual and check all of the thermo sensors and they have all checked out within specs. We also made sure the thermostat was working properly. I’ve got two identical skis, so we even swapped out the ECU units and still the same problem. Finally we blew out the water passage with no issues. Any other suggestions?