2009 Buick Lucerne

I am selling due to buying a 4WD. I have owned 2 years. Bought with 78k miles on it so have put about 70k on it. Mostly highway miles. Newer tires. An emissions code set off about 4 months ago. I have replaced catalytic converter and O2 sensors recently light still on but runs just fine. I change oil every 3k miles. Very clean for its age. Located in Grand Forks