This is a 2500HD truck with the 6.0 L engine. The problem is while driving it will sometimes get the reduced engine power. You can stop, turn the key off for just a few seconds and restart it and it will run fine, sometimes for days or weeks at a time and sometimes only for a few miles. Also when this happens and you restart the truck you will see that the engine hours has cleared to 0, but not everytime. What could be the cause of this? Sometimes the check engine light will come on but not always. Codes from this are unknown at this time.