What Happens When You Run Out of DEF?

[Rolo64]

New to the forum, actually new to being a RAM owner also. I have a 2013 2500 wiIh the 6.7 Cummins. The truck now has about 17K miles on it. I tow a trailer and/or have a truck camper on it maybe 25% of the time. Over the time I have had the truck I have had to add DEF at the rate of about a gallon every 600 miles. When it shows half full or under i can easily add 2.5 gallons, then it will show nearly full. While up in Colorado a few weeks ago I noticed I had let it run down to under a quarter of a tank, so I thought I would let it run down until I got some kind of warning from the truck. That was a couple thousand miles ago, it has been on empty for some time now but nothing has happened at all. If I am not doing any damage to the emission system than I dont see any need to add any more fluid. I hate to take it too the dealer and ask him about it because then he will want to fix it.
So what do you think? Am I hurting anything or should I just keep driving?

Thanks for the help

Ron

 

[4x4Hemi]

With the gmc and chevy trucks i know when you get to low it will limit your top speed, I thought itd do something similar to the dodge if it was low?

 

[Rolo64]

I expected to get a warning on the dashboard, and then if I let it get too low than I expected it to derate the engine. But nothing has happened, nothing at all.

 

[Donelam304]

The Ford 450 we have at work will give you a warning and then cut your power. And the new big firetruck we have does the same.

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[Rotzilla]

I thought I read in the manual that it would limit your top speed to something like 3 mph if I remeber correctly.
I am rather surprised you didn't get a message from the evic, maybe your gauge is that inaccurate. ???

 

[Power247]

I'll go with Rotzilla... Sounds like your gauge is off. If you run out of DEF you will get a warning and if you go long enough the engine will de-rate the power until you get some more. This will be very noticeable.

If you are on the road a lot it is probably worth keeping a gallon with you just in case.

tap tap tappa-roo

 

[Rolo64]

I do have a gallon of DEF with me. Just in case.

 

[dodge dude94]

I was under the impression that the Cummins trucks didn't use DEF and rather used DPFs....

 

[Rolo64]

they havent used DEF in the past, 2013 is the first year for it. At least thats the way I understand it from my dealer.

 

[Stangshcky12]

I was under the impression that the Cummins trucks didn't use DEF and rather used DPFs....

Cab and chassis trucks have since Ram started making them and 13+ have SCR scrubbing

 

[katokahn99]

The 13 6.7s run DEF. My concern is that the OP is only getting 600 miles to half a tank of DEF. There is DEFinately something wrong. But since he is able to drive thousands of miles after it should have run dry and derated, I'm going to say the guage is way off.

Recommendation: FILL it at a DEF pump to make sure it is really getting filled up. Once filled, check to see if you can manually reset the guage in the EVIC settings...if possible. I would have the dealer take a look at it too.

 

[Rolo64]

I might not have made that clear about how much DEF I have used on average over the last 15K miles. On average I use about a gallon every 600 miles, not half a tank every 600 miles.
I am going to fill it up and see how much it takes. I was tempted to quit using it since it apparently has no effect on the operation of the engine, but decided that to use it would help keep the particulate filter clean without going thru the regeneration process.
I appreciate all the input. If I come up with any new info on this subject I will post it here.

Ron

 

[Birddog]

Did you ever get a warning or are you still running with no DEF? It's my understanding that the DEF simply adds moisture to the exhaust to make the black particles of exhaust not disappear but fall to the ground. That way they aren't seen by the naked eye. Maybe someone else has something different by way of what DEF does...

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[Power247]

Def has a high concentration of ammonia which when mixed with diesel exhaust helps turns NOx into pure nitrogen, water, and CO2.
It is a much better design then using a filter to capture the NOx and then use diesel fuel to burn off concentration and then funnel the soot into the intake... :-(

sent thru a cloud of smoke

 

[Sparkyy]

Saw a moving diagram of how the DEF works and what it does, etc.

Doesn't the DEF functionality though rob horsepower from the system or is it better than the old way that Power247 described.

 

[Stangshcky12]

DEF is different from particulate filters
DEF is used to convert NOx to nitrogen, water and CO2 in the SCR catakyst like mentioned

The emissions system still has particulate filters to catch the particulate matter and I do believe fuel is still used as the catalyst to burn out the filter. Clean out is less often in vehicles equipped with SCR catalyst

 

[B-g-K]

There's varying levels of warnings and then derate. Keep it full, its only consumed at 2% of fuel consumption roughly.

 

[Birddog]

Mine goes a lot faster when I put a heavy load on the truck and make it work. If not, just like bgk said, the consumption is very slow.

 

[Birddog]

I towed my 35 ft to Alabama and picked up two 2.5 gallon boxes of DEF before I left. I got back home and had only used one box so I let the truck run out of DEF. The truck didn't go into reduced power like I thought it would. I got where I was going and when I shut it off I poured the other box I had in the truck. In retro spect, I should have turned it back on to see if it ran in reduced power after the cpu reset.

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[Willie maugham]

I was towing my sons jeep, gauge showed full wasn't paying any attention to it pulled over for a pit stop came back to truck still running and had a check engine light on. Drove it another 50 miles got to dodge dealership they pulled the codes and it came up as p249e "so closed loop resistant injector control at limit- flow to high" after pulling injector and replacing gasket cleaned off injector and port tested ohms, everything should be good right? No check engine light on still (figured it would go out lol) under truck scratching my head and used the wrench to play a little drum solo on fuel tank while brainstorming and hit a very hollow def tank duh filled it still check engine light on but will take in today to see if it will clear. No warnings no lights no derating of engine nothing except a very slight sluggishness to it.