Answer
Oct 15, 2025 - 05:57 PM
For the diesel Rams in that range, the DEF (Diesel Exhaust Fluid) fill point depends on which engine you’ve got — but they’re all pretty easy to find once you know where to look:
- 3.0L EcoDiesel V6: The DEF filler is right next to the diesel fuel cap, under the same fuel door. It’s a smaller blue cap marked “DEF.”
- 5.9L Cummins Diesel (older setups): Most 5.9L models didn’t originally use DEF, since they predate the emissions system that needs it. So if yours is a 5.9L, there’s no DEF tank or filler at all.
- 6.7L Cummins Diesel: You’ll find the DEF fill neck under the hood on some early versions, but on later ones (especially 2014–2016 trucks), it’s usually next to the fuel cap, just like on the EcoDiesel. Again, look for that blue cap.
And just in case — don’t mix it with diesel fuel. DEF goes into its own tank; it’s basically a urea-water mix used for the emissions system (SCR), not the engine itself.
