Diesel Exhaust Fluid

Diesel exhaust fluid (DEF) is a liquid that is used in diesel engines to reduce harmful emissions. DEF is a combination of urea and deionized water and is not hazardous or toxic. When injected into the exhaust stream of diesel engines, DEF breaks down nitrogen oxide (NOx) into harmless nitrogen and water vapor. The use of DEF is necessary for diesel engines equipped with selective catalytic reduction (SCR) systems to meet the strict emission standards set by the Environmental Protection Agency (EPA).