Chevy 2500HD 6.6L Diesel. I was driving tonight when I heard a slight knocking sound, the check engine light came on, and I lost function of the gas pedal. I immedaitely became concerned of it being low on oil, but could not believe that to be the case. I shut the truck down and checked the dipstick several times... oil was fine. I started the truck back up and it ran fine; however, the check engine light is still on. Does anyone have any thoughts on what might have caused this to happen? Any thoughts on why the check engine light will not go off?