Diethyl(methyl) (isobutyl)phosphonium hexafluorophosphate, [PF6]-is [P-1,P-2,P-2,P-4] an organic ionic plastic crystal with potential uses as a solid electrolyte in storage and light harvesting devices. In this work, we present a molecular dynamics simulation study for this material covering an extended temperature range, from 175 to 500 K. The simulations predict a transition from the crystalline to a semi plastic phase at 197 K, the onset of cation jump-like rotations at 280 K, a third transition at 340 K to a full plastic phase, and melting to 450 K. Overall, the simulations show a good agreement with the experimental findings, providing a wealth of detail in the structural and dynamic properties of the system.