Where do you live and what's the temperature? is your adblue tank full?
That's a code that says low pressure in the adblue system. You have two tanks. One small heated transfer tank and a large unheated storage tank. Assuming that's filled but frozen solid there's no adblue available to the transfer tank and it sets the code and immobilizes the vehicle. Effin dumb yes but thawing out the car usually fixes that. If you live in hot weather, you're either low on adblue or something else is wrong with the adblue delivery. Obd 2 readers arent very informative on an MB, the best code reader is a star machine which only a dealer or a good independent have.

 

Thanks Max! It could be the cold temperature. I live in Seattle WA but it's not frozen yet. Adblue was just flushed and filled by dealer 2 week ago when the truck was there for the same problem. i'll wait for the check engine error to show up again then send it back to dealer.

 

Unlikely that your adblue is frozen solid as you live in Seattle. You've got something else going on in your adblue tank. Good luck to you.