This is a known problem with DC and several vans have the problem. But no one seems to know or can find out what is causing it. Very few Sprinter owners that have this problem can get it to the shop while the noise is there. I spent $400 trying to have Freigthliner find the problem. Only to be told afterwards that, when they FINALLY duplicated the noise, what they thought was causing the problem really wasn't. But at least I have it on file that there is a noise/problem with the van should something breakdown after the warranty has run out. I just wish DC vans would do a recall on whatever is causing the problem. Because regarless of whatever they are telling us you know that they know what the problem really is. I also wish they would do a recall on ALL EGR valves that are defective.