Question

what is the diesel exhaust fluid (def) used for? a) it reduces oxides of nitrogen (nox) emissions. b) it cools the exhaust components. c) it boosts the diesel fuel cetane rating. d) it keeps the diesel fuel from freezing.

Explanation:

Diesel Exhaust Fluid (DEF) is a key - component in Selective Catalytic Reduction (SCR) systems. It reacts with nitrogen oxides (NOx) in the exhaust stream to convert them into nitrogen and water vapor, thus reducing NOx emissions.

Answer:

A) It reduces Oxides of Nitrogen (NOx) emissions.