It may sound stupid, but make sure to not mount the thermostat upside down. Not sure where I've seen the pic, but someone (probably a dealer or repair shop) posted a pic of someone mounting it the wrong way and they were fixing it. There are a few places to buy that part online - Bakes, SkiDim, etc.

Overheating will throw a code and I think those model years causes the boat to go to limp mode.

Scanners - yes, dealers will have the correct software/tools to plug in. Not like my truck scanner where you buy them on Amazon.

Per error codes, when I threw a low volt code on my 2007, the system will auto clear the code after ?3? successful startup and shut down cycles. Not sure of the exact number of those cycles right now (3 is my guess), but there is a thread on here about it where someone from Indmar posted that info - Larry the Engine Nut. Worked for Indmar. Great dude.