That’s the code for a potentially faulty cat, but it doesn’t necessarily mean the cat is the problem. Take a look at the post by Tester below which shows how the computer compares the pre-cat O2 sensor signal to the post-cat O2 sensor signal. You need to make sure that same test has been done on your cat, and it shows the cat is bad, and not some other problem, like a bad or disconnected O2 sensor.