Diesel Exhaust Fluid

This is a solution that’s injected into the exhaust of diesel engines to reduce emissions.

Why I Looked It Up

I was in Omaha, and almost every gas station has signs for “DEF” in addition to gasoline and diesel.

We don’t have these signs in South Dakota (that I have seen – see below). I had literally never heard of this before.

I looked around for the laws requiring DEF, and I couldn’t find anything specific to Nebraska. An vendor of DEF devices said this:

In the U.S., all heavy and medium duty diesel truck engines produced after January 1, 2010 must meet the latest EPA emissions standards.

So, this doesn’t seem to be Nebraska-specific?

One theory: I don’t live in an area of Sioux Falls that sees a lot of big trucks. Next time I’m in the industrial park north of town, I should look for DEF signs. When I was in Omaha, I mainly on I-80, which is a heavy truck route, which might account for all the DEF signs.