Some 2017 F-Super Duty/2016-2017 F650-750 equipped with 6.7L diesel engines and 2015-2017 Transit equipped with 3.2L diesel engines may exhibit a MIL on with diagnostic trouble code (DTC) P206C stored in powertrain control module(PCM). This may be due to incorrect diesel exhaust fluid (DEF) concentration. Prior to performing Powertrain Control and Emissions Diagnosis (PC/ED) pinpoint test RJ, ensure DEF concentration is checked using Central Tools Refractometer tool number CEN3R201 and if DEF contamination is suspected use the Rotunda Hydrocarbon Test Kit tool number 328-480508.