NHTSA Preliminary Evaluation PE23020

On November 15, 2023, the Office of Defects Investigation (ODI) opened Preliminary Evaluation PE23020 to investigate allegations of loss of motive power in model year (MY) 2016 through 2019 Nissan Titan XD trucks equipped with 5.0L Cummins diesel engines.  The complaints allege the condition was due to a failure of the engine crankshaft.  The purpose of the investigation was to understand the scope, frequency, and safety related consequence of the alleged defect. During the investigation, it was found that the subject vehicles can experience a loss of motive power due to a failure of the crankshaft main bearings which can lead to a fractured crankshaft. This resulted in a loss of motive power and an inability to restart. An analysis of all complaint sources shows many vehicles exhibit knocking, vibration, malfunction indicator lamp (MIL) warnings, and/or poor engine performance prior to a total failure.  Some consumers report driving their truck in for repairs only to be diagnosed with a failed crankshaft.  ODI has not identified any injuries or fires attributable to this failure. ODI is aware of one complaint alleging a non-injury crash involving a curb strike.  ODI is also aware of complaints of overheating starter motors and melted starter motor wiring occurring after prolonged attempts to start engines that have suffered a broken crankshaft. In its response to ODI's January 26, 2024 information request letter, Nissan provided information detailing several material and process changes involved in the production of the subject vehicle’s engine.These changes appear to coincide with incremental improvements in failure rates but there is no indication that a single factor was the primary cause of the failures. Analysis of ODI consumer complaints and manufacturer provided data found that failure rates decreased progressively for each model year. Review of failure mileage found that 50% of the failures occurred by 60,000 miles with a significant decrease in failures af