I have an OM642 in my GL350 so I'm very familiar with the problems around the swirl motor. While that engine is basically the same as what they used in the Sprinter, there are a few differences, so I've got either really good news or fairly good news for you.
Basically, you've got these flaps that are inside the intake manifold which the computer will open and shut depending on RPMs and load on the engine. The idea is to create a little more disturbance in the air to improve emissions, but there really isn't any difference in how the vehicle runs if those flaps aren't moving. What will give you a problem, though, is if the computer puts you into limp mode. On my GL, when the computer thinks that the motor isn't connected or working it throws the MIL and puts the vehicle into limp mode. Super bad. If, however, it thinks the motor is fine electrically but it doesn't see the flaps moving, it throws the MIL, but the vehicle runs just fine. Slightly annoying, but not a big deal.
Replacing the swirl motor is a pain on my car because in order to move a wiring harness out of the way to get to the motor, you have to pull the turbo off. I've heard that on the Sprinter, things can be pushed around a bit to get to the swirl motor without removing the turbo, but I've never worked under the hood of one. If you can get to the motor, a replacement can be had for a bill-and-a-half, but there are a couple different versions out there, so be sure you get the right one. It's also a good time to replace the fuel filter and air filters and check for leaks. Plan to replace the orange seals on the turbo charge pipe and the PCV tube and look up the "elephant nose" mod and consider that. You're looking at paying Mercedes somewhere around $1,300-$2,000 for that job (somebody's got to pay Hamilton's salary!), but if you're familiar with the basic operations of Legos, you can do it yourself for around $300. Pro-tip: Spend a little extra money and buy two or three pairs of the little plastic clips that connect the actuator motor to the flap linkages. You'll also need a set of E-Torx bits which will set you back around $20 at your local hammer store.
What's that, you say? Don't want to spend the time or money? Well, then I've got a deal for you: Do a little eBay searching and find someone willing to sell you a handful of 4.7K Ohm resistors. Should be about $2, shipped. While you're waiting, go get yourself some self-fusing silicon tape, or if you can't find that, a good (and by good, I mean 3M and pretty much only 3M) black electrical tape will suffice. When those arrive, unplug the swirl motor from the wiring harness. Giving it the finger is an optional step but can be quite cathartic. Bend up the resistor so that you can plug it into the center two pins of the wiring harness connector. Wrap it in tape so that it's completely secured and then tuck it away.
At this point, one of two things will happen: You'll either get the MIL lit but the RV will run fine (that's the fairly good news) or there will be no MIL on the gauges and the RV will run fine (which would be the really good news).
Alternately, you can turn it and your wallet over to the Mercedes mechanics. Since they're going to "be in there anyway", you might have them replace the timing chain and tensioner before that starts clattering on you. And you might check to see if you have any oil leaks since the oil cooler seals are notorious failure points that require some pretty serious surgery to get to.
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