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DEF fluid gauge seems stuck & haven't added DEF for months

RiverRam

New Member
Mar 31, 2019
5
1
Truck Year
2014
My 2014 Ram's gauge for the DEF fluid has been stuck on 1/4 for many months. Is it possible that if the tank gauge is stuck, it would keep running without DEF fluid? If so, would it harm the engine or CAT to do so?
I know that if it registers empty, it will not start, but this is something else.
Thanks much
 

BoostN

Administrator
Staff member
Administrator
Jul 27, 2013
4,328
1,143
Truck Year
Not Listed
It'll warn you when it's low... if you have no check engine lights/etc drive it. But, if it's been more then 3 or 5K miles, I would add a 2.5 gallon jug to see if it responds.
 

RiverRam

New Member
Mar 31, 2019
5
1
Truck Year
2014
It'll warn you when it's low... if you have no check engine lights/etc drive it. But, if it's been more then 3 or 5K miles, I would add a 2.5 gallon jug to see if it responds.
Thanks for the response. As the original owner at 150K miles, it always has given notice of getting low. And if I don't have to add DEF if it will keep running, even better. That is, unless it will cause engine damage. That's my main concern. Any thoughts? Thanks much!
 

CVR_71

New Member
Mar 17, 2023
10
8
Truck Year
2016
I got my 2016 two years ago, with just under 166k, and the DEF gauge just touching on red.
I added two 2.5 gal jugs of Walmart DEF when I took it for fuel fill-up, and that was the last I put in until this past January, almost 11k miles later.
It hadn't even gotten down to the same point, it was just barely below the 1/4 mark, finally.
It stayed on/near 1/2 tank for months.

Since you're the original owner, how often do you normally have to add DEF?
Has the ecu been updated lately? If so, maybe that changed the consumption rate?
 

BTdriver

Active Member
Aug 30, 2018
105
45
Truck Year
2015
Running out of DEF won't damage the engine as it's only a treatment for exhaust gasses. The ECM is programmed to progressively limit the trucks speed when DEF runs out. I have heard of some tunes turning off the DEF system. That would also appear to make it possible for someone to turn it off via a programming tool like Alpha OBD. If the injector nozzle is clogged shut, the NOX sensor will "see" it and trigger a code - at least that's what my truck has done.
 

RiverRam

New Member
Mar 31, 2019
5
1
Truck Year
2014
Thank you all for your comments! Good to know it won't damage anything without DEF. I normally go through a tank of DEF every 15k or so. Always been a sipper, but it has been longer now. I have never messed with any programing and only bring the truck to dealer for recalls, which as we know, there have been many.
 

John Jensen

Well-Known Member
Mar 22, 2016
954
491
Truck Year
2016
Here's the DEF process:
Selective Catalytic Reduction (DEF Process)- when the SCR temperature reaches 500 degrees and NOx reaches a certain level, DEF is injected into the SCR (EGT4 sensor). NOx levels trigger the DEF injection and also determines the quantity of DEF.

Strictly a matter of how you are driving. I see no problem, and as BTdriver said, it's an exhast system process, has nothing to do with the engine. The engine is safe from harm.
 

CVR_71

New Member
Mar 17, 2023
10
8
Truck Year
2016
...... I have never messed with any programing and only bring the truck to dealer for recalls, which as we know, there have been many.

The dealer visits was what I was thinking of, my truck had a recall, last year?, for a programming update (dealer checked said it already was installed), I thought maybe something like that might have affected it?
 

FlyEco2122

New Member
Jan 2, 2025
3
2
Truck Year
2016
My 2014 Ram's gauge for the DEF fluid has been stuck on 1/4 for many months. Is it possible that if the tank gauge is stuck, it would keep running without DEF fluid? If so, would it harm the engine or CAT to do so?
I know that if it registers empty, it will not start, but this is something else.
Thanks much
You need to replace your def pump. I had the exact same thing happen right after 100k. I replaced the pump and everything has been fine ever since. It is a very easy fix.
 

A standup guy

New Member
Oct 12, 2021
27
4
Truck Year
2016
I personally never fill the DEF all the way up. DEF has a shelf life and will get crusty when old gumming the injector and gauge up. Least thats the way I think about it. I want to be putting fresh stuff in every so often and mine doesn't go through it very fast which is Def a nice thing about the EcoDiesel. I've heard some engines really go through it.
 
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