Kartir's own inscriptions and the Paikuli inscription of Narseh together document his public career into 293 CE, but no source records what became of him after that year or gives an actual death date.
What would resolve this A dated Sasanian inscription, seal or administrative record naming Kartir after 293 CE, or an external source recording his death.
OpenSasanian history, Zoroastrian studies, Iranian epigraphyTouraj Daryaee, Sasanian Persia: The Rise and Fall of an Empire