Diesel engines can be more efficient than gasoline engines, but that's largely due to DEF. Here's what it does, how it helps, and what happens if you run out.

Engine, Truck Manufacturers Support EPA Easing Derate of SCR Diesel Emissions Controls School Transportation News News ...

This change will let operators fix issues without their equipment shutting down, write the EPA's Lee Zeldin and the SBA's Kelly Loeffler.

DEF is used to reduce harmful nitrogen oxide (NOx) emissions from diesel engines. (Photo: iStock) Under EPA’s new guidance for heavy-duty trucks, after a fault is detected, only a warning light will ...