Heat the oil in a heavy large frying pan over medium heat. Add the onion and garlic and saute until translucent, about 5 minutes. Add the carrot and celery and saute until the vegetables are tender, about 5 minutes. Add the turkey and saute 6 minutes or more until the pink is gone and meat is cooked. Add the marinara sauce. Decrease the heat to medium-low and simmer gently for 15 minutes to allow the flavors to blend, stirring often. Stir in the basil. Season the sauce, to taste, with salt and pepper.