What is DEF, and why is it important?

November 15th, 2022 by

What is Diesel Exhaust Fluid? Diesel Exhaust Fluid (DEF) is a mixture of ⅔ deionized water and ⅓ urea that is added to your diesel fuel via a separate tank and control system. DEF is meant to reduce the emissions from a diesel engine. If your diesel medium or heavy-duty pickup is newer than 2010,