Diesel Exhaust Fluid (DEF)

Diesel Exhaust Fluid (DEF) is a non-toxic, colorless, odorless, and nonflammable fluid used in diesel engines in order to reduce emissions of nitrogen oxide (NOx). DEF is injected into the exhaust stream of Selective Catalytic Reduction (SCR) systems to convert NOx into nitrogen and water. DEF has a shelf life of one year and is typically stored in tanks on the vehicle. When used according to manufacturer instructions, DEF can reduce NOx emissions by up to 90%, helping to improve air quality and reduce greenhouse gases.