One problem related to engine knocking noise has been reported for the 2006 Dodge Sprinter. The most recently reported issues are listed below.
I was driving on a relatively flat road and heard a pop noise from the engine area and the vehicle lost approximately 40 to 60% engine power, I was able to get it to my home less than 5 miles distance, I got it into a shop for repairs and they were not an authorized warranty repair shop, which cost me $404. I then had the vehicle towed to an authorized repair facility approximately 35 miles away.