Im not a diesel guy but i was looking throught the forum. I know that the schucks O'reilys ive been to, you just you say the cel is on and they ask for your i.d and they give you the scanner and you do it yourself. Plug it in turn ignition on and i believe press the green button. It will read for codes and display them. There should be a button that has a little eraser on it. Press it and it should ask if you want to erase the code. Id have to look at a reader to make sure that is correct. But its something along those lines. Good Luck! Anyone feel free to correct me if im wrong.