I bought a 08 6.7 yesterday with the g56 and 342 gears. Truck has 100k on it. And I love it. But while driving last night I got in it kinda hard coming up a hill and the check engine light came on and the over head say oil change required, the oil had just been changed. I cycled the key for codes and nothing. This morning I got in it and the check engine light had went off, and I followed the steps to get rid of the oil change on the over head. This after noon I passed a car and got on it pretty hard again and the check engine light came on again. Also with no codes. The over head says system ok. Any ideas what it is? The truck is deleted but doesn't have a tuner to my knowlege. Atleast I can't see one any where under the hood.

 

Forgot to add the truck runs and drives great. With the light on, doesn't cut out and I checked my milage hand calculated was 21.6 yesterday.

 

it has a tune of some kind on it. oil change has nothing to do with check engine light. make sure the valve cover filter has been changed. also 07.5 and 08 needs a rail plug put in. they have a weaker relief valve than later models. when it does it again you need to get the code.

 

I cycled the key to get the code as soon as it happened the first time and it came up ---- then done.