My Impreza has been leaking oil, I think from the head gasket on the right cylinder bank. Could be the valve cover gasket, as the exhaust still seemed clean. But all of a sudden, the exhaust is blue and the check engine light came on. It’s code P0420, so it’s a catalytic converter issue. Is it possible the two problems are related? Could I have burned enough oil to foul the converter?
Thank you very much