MD has it's quirks, for sure. If you haven't already done so check out the "engine protection session". It stores mileage/time stamped eng protection faults. (low oil, low coolant,overheat)info. Which is useful for determining if someone ran it out of coolant, overheated etc, and when it occured in eng hours or mileage. Int'l continues to resist time stamping and occurence counts for there other fault codes which is incredibly foolish in my opinon. If the last tech that worked on it neglected to clear faults, when finished you wouldn't know it. When they come in with multiple inactive faults this can be a problem especially with intermittant concerns.