Diesel Exhaust Fluid (DEF) for Dummies

MOPAR DEF Jug

If you own a 2013+ Ram diesel you know that you need to use diesel exhaust fluid (DEF) or you run the risk of going in to limp mode. You probably have some questions. What does DEF actually do? Does DEF go bad? Are any brands of DEF better than the others? DEF is made up of two things, Urea and de-ionized water. This mixture (32.5% urea/67.5% water) is sprayed via an injector in to the exhaust to lower the N0x emissions emitted from your diesel truck. If you decide…