A code is neither a symptom nor a diagnosis. Replacing parts based solely on a code is just guessing. Guessing is by far the most expensive and time-consuming way to repair a vehicle.
I have seen many people actually install additional problems into their vehicles, by replacing functioning parts with inexpensive aftermarket parts during the course of guessing.
I would recommend having it properly diagnosed instead.
I would second this .
I have tried a Delphi scan tool! And in short not too impressed! My youngest brother loaned me one for trial ! He has a shop in Gloucestershire!
In fact Delphi in the USA is very US product centric policy and doesn't "do Benz very well"!
It will lead you up the garden path.
I do have three Autologic scan tools "2 blue box" "1 grey" plus others for my guys to use.
Its one of the few decent automotive diagnostic scan tool products that the UK makes and supplies worldwide, but expensive to buy.
You might want to call Autologic (in Wheatley Oxen) and see if they can locate a shop near you to do a diagnostic scan,
We don't have this exact Sprinter model in the US but the set up is similar to the OM651 in 2103 onwards Sprinters .
Yes vacuum can be a big problem and so can be the vacuum operated water pump clutch.
Essentially coolant gets sucked into the vacuum system and the liquid gets dumped into the engine crankcase simply by way of the vacuum pump which is mounted low down on the crankcase. If left for any time it will wreck the engine.
Although the pump has one way valve on it and visible . The 19mm plastic hose itself has a further one way valve built into it before it reaches the servo check valve. Its prone to failure !
On NAS Sprinters with the OM 651 the vacuum is stored in a wedge shaped vacuum tank near the valve cover . The bloody thing has a habit of separating itself at the base section & then leaking stored vacuum .
What I will tell you is that if coolant gets running through the vacuum system, it has a habit of wrecking the solenoids. So they should be checked and that includes vacuum hoses for leaks.
We use a vacuum pump to raise the depression to the a minimum of 27/28" HG held for 30 minutes .
Hope that helps
Dennis