I'm not a trucker, but a search for DEF problems led me here! In reading through the posts, I'm not the only one with Sprinter CEL and DEF troubles.
I bought my 2011 3500 long tall from a trucking company with 173k on it, and it now has 192k on the odometer. They trade them in every couple of years, so it wasn't sold because of the error code problems, as I know the regular driver as a friend. He says they did regular maintenance, but do use generic DEF fluid from a 55 gal drum, didn't worry about fluid expiration, and probably didn't worry about the low ash oil requirement. In the two years I've owned it, I've used the 2.5 gal Peak BlueDEF containers sold by Wallmart, and have kept an eye on manufacturer dates, along with use of low ash oil.
Passing smog was not a problem in Cali until this month. Two years ago it was just a matter of not having the CEL on and it would pass, but now Cali requires there be no fault codes in memory, and no more than two monitors not closed (various sensors). My CEL could be cleared simply by going through 4-5 engine restarts, but would come back on as soon as I hit the steep grade on my way home. And there would always be at least one fault code in memory, P2BAD (generic scanner fault which has to do with the diesel particulate filter), and sometimes P2BA9, which has to do with DEF quality.
Whenever I added a container of DEF the P2BA9 code usually appeared after hearing those horrendous beeps and 10 ReStarts remaining message, then all would return to normal after the DEF check message ran its check. When I first got the van and the first time that ReStarts remaining message appeared, but didn''t clear by adding fluid, I ended up draining all of the DEF out, and started with 5 gallons of fresh liquid, and the ReStarts message then cleared.
In my efforts at fixing problems, and wanting to put off paying for a new dpf (trucking company told me they need new dpfilters at 175k), I discovered something that may be of use for you guys who are worried about having the 10 ReStarts message appear while on the road. Yes, generic scanners will clear fault codes from memory, but they will not get rid of the ReStarts Remaining message until the problem that caused the message is fixed.
There is a computer program called MB Star, or Star Diagnostic System, google both, that I hear will reset the ReStarts Remaining message, but verify before purchase as not all systems will do this. The message will appear again until the underlying problem is fixed, but at least you should be able to continue down the road knowing you can add more restarts. It will also run the regen cycle on command. This is the program used by MB dealers and mechanics. Supposedly it is not available to the general public, and costs something like $3000 anyway, but those crafty Chinese hackers have come up with a clone of it for a few hundred bucks.
It usually bothers me to support hackers, but since MB is doing its best to screw me with super expensive repairs for highly secretive problems, that bothers me even more!
I have not purchased the system myself (yet), but you can read more about these diagnostics gizmo's here:
http://www.benzworld.org/forums/r230-sl-class/1573730-chinese-mb-star-scanners.html
http://www.mercupgrades.com/star+diagnosis+information-article-24.html
http://www.cardiagnostics.be/-now/DAS-WIS.htm#Mercedes-Benz_Star_Diagnosis_System_(SDS)
