What Is Diesel Exhaust Fluid and Why It’s Important
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Diesel exhaust fluid (DEF) is a vital component of your truck’s engine. It has been required by the U.S. Environmental Protection Agency in all diesel engines in use in the United States since 2010, including heavy-duty equipment. If you’re wondering what DEF for diesel is, you’ve come to the right place. Find out everything you need to know about diesel exhaust fluid with our handy guide from International Used Truck Center.
What Is DEF?
Diesel exhaust fluid turns harmful nitrous oxide into water and nitrogen in your vehicle’s diesel exhaust. DEF works through a chemical process in selective catalytic reduction (SCR) systems installed as an emissions control device on vehicles.
How Does DEF Work?
It uses a blend of deionized water and urea, which chemically converts nitrous oxide in exhaust into nitrogen and oxygen. Your vehicle injects DEF into the exhaust pipe, which heats the liquid to decompose it into ammonia. Within the SCR aftertreatment device, the nitrous oxide is reduced by the ammonia into water and nitrogen.
Why Do We Need DEF in Diesel Engines?
Because nitrous oxide as a diesel exhaust causes smog, which causes all kinds of breathing problems for humans in big cities like Los Angeles, Phoenix, and Pittsburgh. DEF converts nitrous oxide into its component atoms using a special device. And the EPA mandates its use.
How Much Diesel Exhaust Fluid Should I Use for My Vehicle?
Typically, you need 1 gallon of DEF for every 200 gallons of diesel fuel. If you load 400 gallons of fuel, your semi will need 2 gallons of DEF.
What Happens When I Run Out of DEF?
In the United States, your diesel engine will not start if you run out of diesel exhaust fluid. That’s because your DEF reservoir detects how much of the fluid you have in the tank.
Can I Substitute Water for Diesel Exhaust Fluid?
No, you cannot because the system will identify it as bad DEF. Even if you could get your engine to start, water defeats the purpose of DEF in your engine.
Where Can I Order DEF?
The best way is to order it through a wholesaler to get quality DEF. It has a shelf life of about 12 months. In a pinch, you can get some at an auto parts store or refueling station.
Get More Truck Tips About DEF With International Used Truck Center
Now we’ve answered, “What is DEF for diesel?” and other questions. Want to know more? Read our guide to DEF freeze and how to keep your truck running with quality DEF. We’re happy to help in any way we can!