I am considering buying a used 2013 Audi Q5 with 25K miles. The day I was supposed to see the SUV the check engine light came on–the owner was apologetic and very upfront with me. The catalytic converter had to be replaced. The dealership could not give a good reason why this happened. During the winter, the owner backed into a pile of snow–and dented the underpanel in the rear that has since been replaced. Could this have caused the cat problem? The car does have a warranty 5 year/50K that would come with it. What are thoughts about buying this car given this problem (now replaced) that has appeared? Is it likely there are other underlying issues?