Forum Discussion

precioustime's avatar
precioustime
Explorer II
Jul 20, 2014

DEF Fluid in MB Diesel Engine?

I have a 2014 MB Diesel Class C rv. Had new experiences with DEF fluid for the engine. I know when it is low a signal comes on the dash that represents an engine. If you ignore it for too long another signal comes on stating that you have 10 more starts before it has to be towed to a dealer and checked by a computer. Then it is time to pour a couple of gallons of DEF fluid to erase that sign. Is it better to check the fluid roughly every 1000 miles, add fluid to fill or wait till the signal comes up on the dash then add 2 gals? I hear if you just turn the key after adding the fluid but not turn on the engine the dash sign will go away. Any information on DEF fluid will be appreciated.
Class C
  • bobojay5's avatar
    bobojay5
    Explorer
    Jul 21, 2014
    Dakzuki wrote:
    First off, your owners' manual is the definitive source of information on your vehicle....not an RV group. You need to learn what those indicator lights mean and what to do with them. The Sprinter manual is very complete and informative. Read it and become familiar with your vehicle. It is a wise investment in time.

    I have the older (big) DEF tank. If the light comes on I put DEF in. If I'm going on a big trip I may throw some more in so I don't have to worry bout it on a trip. Mine will give me 20 starts after the DEF light comes on.

    DEF is Diesel Exhaust Fluid. It is a urea solution that is injected into the exhaust (in conjunction with a catalyst) to help reduce oxides of nitrogen.


    What dakzuki says. I'm getting about 6k+ miles between fills on the 3.2 gallon under front fender tank. Also the non-Mercedes owners that replied...all I can say is you don't own a Sprinter. It's in it's own world of complications
  • gjcummings's avatar
    gjcummings
    Explorer
    Jul 21, 2014
    Join the Sprinter Forum at http://sprinter-source.com/forum/index.php

    for all you ever needed to know about your Sprinter. Get the DEF at Walmart or any auto parts store. 2.5 gallon jug should all go in when you light comes on. You have a small tank. Light should go off within 3-4 starts if not right away.

    Plenty of time to get DEF after light comes on.
  • Dakzuki's avatar
    Dakzuki
    Explorer
    Jul 20, 2014
    First off, your owners' manual is the definitive source of information on your vehicle....not an RV group. You need to learn what those indicator lights mean and what to do with them. The Sprinter manual is very complete and informative. Read it and become familiar with your vehicle. It is a wise investment in time.

    I have the older (big) DEF tank. If the light comes on I put DEF in. If I'm going on a big trip I may throw some more in so I don't have to worry bout it on a trip. Mine will give me 20 starts after the DEF light comes on.

    DEF is Diesel Exhaust Fluid. It is a urea solution that is injected into the exhaust (in conjunction with a catalyst) to help reduce oxides of nitrogen.
  • lanerd's avatar
    lanerd
    Explorer II
    Jul 20, 2014
    Hummmm... not sure if you're confused or I am. Typically, it's me. In any case, the DEF is NOT for the engine...it's for the exhaust system. And I'm not sure why you would have an "engine" indicator when you are low on DEF.

    My coach has a dashboard digital readout that shows the level of fluid in the DEF tank, plus there is a gauge on the tank itself. I usually always add the DEF when the two gauges show I'm down to around 1/2 tank. I would NEVER let it run down to where you get a notice that you only have 10 more starts, just like I would never let my diesel fuel run down to 1/4 tank.

    Ron
  • dbbls's avatar
    dbbls
    Explorer
    Jul 20, 2014
    I fill it up when I get the message. I can go about 5000 miles on a tank.

About Motorhome Group

38,705 PostsLatest Activity: Jan 26, 2025