Technical Service Bulletin 21N02 — 2015 FORD F-550 SD

Certain 2013-2016 Model Year F-Series Super Duty 6.7L Diesel and 2015-2019 Model Year Transit 3.2L Diesel Vehicles – Front NOx Sensor Warranty Extension In all of the affected vehicles, the onboard diagnostic (OBD) system initially contained a software error that prevented illumination of the malfunction indicator light (MIL) if a certain fault was present in the front NOx sensor. Since the PCM was reprogrammed under Emissions Recall 21E01, the OBD system is now able to detect this NOx sensor fault previously masked by the software error and can light the MIL if this fault is found to be present