What Is Diesel Exhaust Fluid Used For?

If you have been to a gas station or auto parts store lately, you’ve probably seen containers of DEF for sale. Diesel exhaust fluid is an additive required in medium- and heavy-duty diesel engines since 2010. It helps reduce emissions so they run cleaner. Failure to use it can lead to reduced performance — if your truck starts at all. Here’s what you need to know. 

Reduction of NOx Emissions

Pure diesel exhaust contains high levels of particulates and nitrogen oxide gasses. These are harmful to the environment and contribute to greenhouse gasses in the atmosphere. Additionally, it is listed by oversight agencies as a Group 1 carcinogen, meaning repeated exposure is likely to contribute to cancer. That puts it in the same category as many things you would likely try to avoid in daily life. However, if you drive a diesel truck, you can’t really get away from it.

What you can do is drive a vehicle that uses diesel exhaust fluid to reduce harmful emissions. DEF combines with diesel exhaust, generating a chemical process to reduce the levels of nitrogen oxide gases. Once exhaust passes through the catalytic reduction system, it is made up of mostly nitrogen and water with a small amount of C02. This is much less damaging to the environment compared to NOx. 

Selective Catalytic Reduction (SCR) System

Your truck is equipped with a specialized selective catalytic reduction system. This evolved over the years as a way to manage NOx emissions from diesel engines. As particulate-rich exhaust leaves your engine, it goes through a primary filter. Once leaving there, it combines with DEF and goes into the SCR catalyst before entering the rest of the exhaust system. The result is tailpipe emissions that are primarily nitrogen and water with very little NOx. 

Special components inject the additive into the system. Therefore, a Ford and Ram DEF injector will be designed differently so they can work most effectively with the appropriate vehicle’s engine. If you need to replace your DEF injector, it’s a good idea to use a VIN lookup tool to find the correct part. 

Proper DEF Levels

As with any fluids in a car, you must keep up with DEF levels. However, your truck actually consumes this additive, just like it does gasoline but at a slower rate. Therefore, you will want to keep a very close eye on the level.

Your truck is programmed to take protective steps if your DEF tank empties. For some engines, that means reduced performance or a limp mode. For others, it means your truck will not start. That’s why you always want to be aware of how much diesel exhaust fluid is in the tank and buy more before you run too low. 

DEF is an important additive that helps diesel engines meet environmental standards. and most trucks built after 2010 require it for proper operation. Using it reduces harmful emissions and helps promote personal safety. Shop online auto parts stores for the right diesel fluid and additives for your truck.