Today I went to check out a used 2006 Dodge Ram 2500 4x4 with the Cummins 5.9 diesel. It has just shy of 100,000 miles on it. The truck appears to be in very good overall condition but there was one thing that stood out to me. When the salesman brought the key out to start it, he first popped the hood and replaced a fuse. He said that was their anti-theft system. Once he fired it up I sat in the drivers seat and noticed the check engine light was on. I asked the salesman what codes were being indicated. He said that they would read it but it was probably something simple. After looking over the rest of the truck I came back to the issue of the check engine light being on and made it clear that it was disturbing to not know why the light was on. The salesman then made a phone call and came back to tell me that the check engine light is on because of them removing and replacing the fuse. Does that make any sense at all?