Definition of node. 1a : a pathological swelling or enlargement (as of a rheumatic joint)b : a discrete mass of one kind of tissue enclosed in tissue of a different kind.
Diesel exhaust fluid (DEF) from a separate tank is injected into the exhaust pipeline, where the aqueous urea vaporizes and decomposes to form ammonia and carbon dioxide. Within the SCR catalyst, the NO. x are catalytically reduced by the ammonia (NH. 3) into water ( H2O) and nitrogen (N.
DEF is a key component of Selective Catalytic Reduction technology, developed to meet the strict EPA and CEPA diesel emissions standards in place since January 2010. The purity of your DEF product is critical as impurities will cause the fluid not to work properly. 1  This means: 2  Your vehicle may not be meeting the emissions standards â you may be liable to fines. 3  Your engine may use more fluid than required. 4  You may not achieve optimum fuel consumption.