Rather you than me re picking up a boat with next to no oil in the engine! I would have to say connect it to the diags as the ECU will remember certain faults such as no oil pressure especially if its gone into limp mode at some stage. Having said that it could be caused by another completely unrelated issue which maybe why you haven't had a response to your question yet as its pretty generic, dealer that services any boat with an Indmar engine should be able to retrieve the code i.e. Skiers Choice, Mal, MasterCraft... if its specific to Indmar engines.
BTW I would have thought this is basic stuff that your "maintenance service" as advertised on your web site should be able to answer! Anyway best of luck with this one....