Hours usage question

[merlin25]

I recently purchased a 2001 22 foot Grady White with a 2005 200 HPDI. Dealer said there wasn't an hours gauge but when they hooked up the computer to the motor they got 402 hours. I was doing some cleaning and noticed a Yamaha hours gauge tucked up under the main console (right behind the wheel but hard to see). That gauge says 828 hours. I have put about 5-6 hours on since I bought it. My thoughts seem to be 1) dealer lied and the motor had double the hours; 2) gauge is reading hours from the 2005 motor as well as original 2001 motor; 3) Motor really read 402 hours on the computer and the gauge is just wrong. Any thoughts or other options?

[boats.net]

The hours recorded by ECU(ones that show up diagnostic program) are engine run time only and is the most accurate. The hours recorded by most hour meters is ignition key on time and often will be a higher reading.