2015 equinox getting P0420 code so im figuring its the catalytic converter. Has anyone ever delt with this warranty? Says its 150000 miles or 2030. Im at 109000 If it is the cat will the chevy dealer try ro find any reason not to fix it? Or is it as easy as paying for the diagnostic. And if it the cat the will replace it? Any other help or suggestions would be appreciated in the process.