What is DEF and Why Do I Need it?

If you own a modern diesel engine vehicle, you likely know about DEF. DEF stands for Diesel Exhaust Fluid, and it’s a critical component for reducing harmful emissions. In this article, we will explore what DEF is, how it works, and why it is essential for your diesel engine vehicle.

What is DEF Fluid?

Diesel Exhaust Fluid (DEF) is a non-toxic, colorless, and odorless solution that consists of purified water and urea. It is injected into the exhaust system of diesel engine vehicles to reduce nitrogen oxide (NOx) emissions. DEF is not a fuel additive, and it is not mixed with diesel fuel. Instead, it is stored in a separate tank on the vehicle and injected into the exhaust system when needed.

Orange box of AutoZone brand diesel exhaust fluid

How Does DEF Fluid Work?

Diesel Exhaust Fluid works by converting NOx emissions into harmless nitrogen gas and water vapor. The process occurs through a process called Selective Catalytic Reduction (SCR). When the exhaust gases pass through the SCR catalyst, they react with the DEF, which breaks down the NOx emissions into nitrogen gas and water vapor. The SCR system ensures that the exhaust gases meet the stringent emission standards set by the Environmental Protection Agency (EPA)

Why Do You Need DEF Fluid?

If you own a diesel engine vehicle, you need DEF because it is required by law. The EPA has mandated that all diesel engine vehicles manufactured after 2010 must meet strict emission standards, which include reducing NOx emissions by up to 90%. DEF is a critical component of meeting these emission standards. If your vehicle’s DEF tank runs out of fluid, it will trigger a warning light, and your vehicle’s performance will be limited until the tank is refilled.

Benefits of Using DEF Fluid

In addition to being a legal requirement, using Diesel Exhaust Fluid has several benefits for diesel engine vehicle owners. These include:

  1. Improved Fuel Efficiency: Using DEF can improve your vehicle’s fuel efficiency by up to 5%. This is because the SCR system reduces the amount of fuel needed to power the engine by optimizing the combustion process.
  2. Reduced Maintenance Costs: Running DEF can reduce your vehicle’s maintenance costs by keeping the exhaust system cleaner, resulting in fewer repairs and longer service intervals.
  3. Environmentally Friendly: DEF reduces the amount of harmful emissions that your vehicle produces, making it more environmentally friendly.

How to Use DEF

Using Diesel Exhaust Fluid is straightforward. Most diesel engine vehicles have a separate tank for the fluid, which is typically located near the fuel tank. To use DEF, you need to fill the DEF tank with a DEF solution that is specifically designed for your vehicle. It is essential to use the correct type of DEF, as using the wrong solution can damage your vehicle’s engine and exhaust system.

When Should You Refill Your DEF Tank?

Most diesel vehicles have a warning system that alerts you when the DEF tank is running low. The warning light will usually come on when the tank is about 20% full, and you should refill the tank as soon as possible. It is essential to keep the DEF tank full, as running out of DEF can cause your vehicle to enter a limited performance mode.

Diesel Service at Scott’s U-Save

If you own a diesel vehicle and are looking to have it serviced, Scott’s U-Save is your premiere option. Our expert diesel technicians will ensure your car or truck is not only stocked up on DEF but also running healthy and prepared for future driving!

Call or schedule an appointment with us online today at any of our three locations!

Schedule An Appointment

Whether you're shopping for tires, looking to lift your truck, or need auto repair, Scott's U-Save is here to serve you! Schedule an appointment online or call today!

Get In Touch