When do you get a tune up

Hello, A "tune up" is a term often used to describe when engine maintenance should be performed, such as replacing spark plugs. For your Nissan Sentra, this is best done at latest 105,000 miles. You could do it sooner, but that's the "severe duty" schedule recommendation. Your engine air filter should be replaced every 15,000 miles or so. Other than that, there are no recommendations. Hope this helps.