N192266750

N192266750 - Service Update. On certain vehicles that are equipped with a 6.6L diesel engine, may have one or more of the following conditions exist: 1.The instrument panel cluster may incorrectly display the message ?DEF Low? when a diesel engine fluid (DEF) controller internal fault is detected (DTC P20FF), instead of displaying the proper ?Service DEF System? message. 2.The customer may complain of excessive engine fan noise at a low vehicle speed. 3.Under certain conditions, the diagnostic system may set one of the following DTC?s when there is no problem with a component: (P20EE, P226D, P16F3 and P129F). Dealers are to reprogram the engine control module.