Background: DEF systems in modern diesel engines are key to reducing Nitrous Oxide (NOx) emissions  and protecting the environment.   The DEF system is a combination of software, hardware and DEF fluid that enable this important task.  Recently there has been a pandemic of failures affecting one of the elements of the DEF system called the DEF sensor.  The origins of this “DEF pandemic” are not  known for certain but the failures may be related toLearn More