I totally agree with resindiana about Cummins services being overpriced. But my opinion is that you can solve almost all problems regarding the car/engine yourself without paying any amount.
Fortunately there are plenty of videos on youtube that explain how to fix vehicle problems.
All you need to know is what is wrong with your car (what the code means) and that can be found out on the many engine-code sites. My personal favourite is http://engineservicelight.com but there are also many other sites you can visit.