Merc DDT question - hours don't add up

[STV_Keith]

Looking at a ECM report, the total hours is higher than the sum of the hours at each RPM range. Why would that be?

Motor is a 2003 Merc 300x.

[kct11]

Run history has been reset/cleared. It doesn't reset total hours though.

[HydroSkreamin]

Could have been reprogrammed.

[Wayne Cammidge]

I always reset the Run History when I do a service
Easy to see how much running it has done since I was last in the motor.
Just a quick total up gives me an idea of how much the engine has been used since it was last serviced

[kct11]

Me personally, I don't care for that way of thinking. Document the hours after service and move on. I get nervous about clearing them on accident evey time my ddt is hooked up. Original poster probably would love to know where the missing 250ish hours were spent...and potential buyers if it was for sale.

[flabum1017]

looks like fish boat hours, most of the hours at low speed.....

A buddy of mine has a couple 2004 225 opti's, one engine resets the total hours to 0 every time he shuts it off.............

[Tango]

The total hours are always there... so having a run history is key sometimes for solving life's stupid Mercury issues.