DEF (Diesel Exhaust Fluid) is a crucial component in modern diesel engines that helps reduce harmful emissions. This fluid is sprayed into the exhaust system of diesel engines to break down harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor. This process is known as selective catalytic reduction (SCR). DEF is a high-purity solution of urea and water, with a chemical composition of 32.5% urea and 67.5% deionized water. When the DEF is heated up in the exhaust system, the urea breaks down into ammonia, which reacts with NOx to form nitrogen and water. The result is a reduction in emissions of up to 90% compared to conventional diesel engines. DEF is stored in a separate tank in the vehicle and is only used when the engine is running. The amount of DEF required is dependent on the engine size and driving conditions, but typically, a vehicle will use between 2-5% of its diesel fuel consumption. It is important to note that DEF is not a fuel additive and does n