What does DEF stand for in the context of diesel engines?

In the context of diesel engines, DEF refers to Diesel Exhaust Fluid. It is a mixture of water and urea and is used in selective catalytic reduction (SCR) systems to reduce nitrogen oxide (NOx) emissions from diesel engines. When injected into the exhaust stream, DEF reacts with nitrogen oxides to convert them into harmless nitrogen and water vapor, which helps meet stringent emission regulations.

The use of DEF is essential for modern diesel vehicles and equipment that comply with the EPA's Tier 4 emission standards and other international regulations aimed at reducing environmental impact. Proper understanding and use of DEF are crucial for maintaining the efficiency and regulatory compliance of diesel engines.