Yes its due to an issue in the ecu that causes the cat to fail. Its not an 02 sensor fault its telling you the 2nd cat is bad so to answer your question yes it will fix your problem.

 

a highflow cat is not going to fix your problem. the code is telling you that the catalytic converter that is built into your exhaust manifold is bad and overheating. the 2nd cat under the car isn't even monitored by the system. your o2 sensor goes in the front of the cat at the inlet. not on the outlet. i would recommend buying the rrm header and installing a cel eliminator to fix the problem. the aftermarket header will give you better flow and also remove that stupid cat. i have a rrm header, magnaflow highflow cat, and piggyback for sale since i went turbo. pm if interested