price for intake manifold gasket and relation to check engine light

Without looking at it I could not confirm the diagnosis. A leaking intake manifold gasket could cause a lean condition and the check engine light to come on. However it would seem that a vehicle that new should be covered under a warranty, Either the vehicle manufacturers warranty, or the federal emissions warranty. I would suggest looking into the warranty, and if you do fall outside of that, then $270 is about what I would expect that kind of repair to cost.