Diesel Exhaust Fluid (DEF)

Diesel Exhaust Fluid (DEF) is a solution used in modern diesel engines to reduce the emissions of nitrogen oxides (NOx) produced during combustion. It is a key component of selective catalytic reduction (SCR) technology, which is employed to meet stricter emission standards for diesel vehicles and engines, especially in commercial trucks, buses, and heavy machinery.

DEF is a clear, non-hazardous fluid that is composed of approximately 32.5% urea and 67.5% deionized water. It is stored in a separate tank in the vehicle and is injected into the exhaust stream before it passes through the SCR catalyst. Inside the catalyst, the DEF reacts with the NOx emissions and converts them into harmless nitrogen gas and water vapor. This chemical reaction helps to significantly reduce the emissions of nitrogen oxides, which are harmful pollutants that contribute to air pollution and smog formation.

It's important for vehicle operators to ensure that the DEF tank is regularly refilled, as the consumption of DEF is related to fuel consumption. Most modern diesel engines are equipped with sensors and warning systems that alert the driver when the DEF level is low. If a vehicle runs out of DEF, it may go into a reduced power mode or even prevent the engine from starting, as a measure to ensure compliance with emission regulations.

DEF availability has become more widespread as emission regulations have become stricter. It's commonly available at gas stations, truck stops, and automotive supply stores. It's important to handle DEF with care and to use only certified DEF to ensure proper function and compliance with emission standards.