Model-based statistical process to determine diagnostic limits in a sensor position system for a turbocharger

A method of determining diagnostic limits for a vane position sensing system installed in a variable nozzle turbocharger (VNT). The method includes defining mechanical input probability distribution functions (PDFs) of the VNT, describing the vane position sensing system in terms of component models and defining component parameter PDFs for parameters associated with the component models. Vane position signal PDFs based are generated on the mechanical input PDFs, the component models and the component parameter PDFs, and diagnostic limits are set for the vane position sensing system based on the vane position signal PDFs.