This Preliminary Information communication provides information to the technician that some vehicle may have an ?Exhaust Fluid Quality Poor? on the Driver Information Center or a diesel exhaust fluid warning lamp on or other exhaust fluid quality related concerns. Technician will inspect the diesel exhaust fluid for contamination. Technician should use Service Information for Contaminants in Diesel Exhaust Fluid Diagnosis and use special tool J26568 or EN50422 Diesel Exhaust Fluid Refractometer for fluid testing.