2006 Dodge Magnum Check Engine Light Went On Diagnosed Catalytic Converter

My check engine light went on and it was diagnosed with catalytic converter failure. I was told that this will be covered under the 8 year 80,000 mile warranty. Then they said that it failed because of something wrong with then engine. I have yet to have them check this out and figure out the engine problem, but is it possible that there is an engine problem a result of the cat. converter failure? If so, shouldn't the engine repair be covered under the cat. converter warranty since the cause was the converter failure to begin with?