So i’ve been driving a used 2005 Toyota Corolla for about a year now. It has 244,500 miles on it. I recently swapped in a new battery & a grade A alternator on it. The dreadful check engine light came on & when I took it intk autozone to get the code read, it gave that awful P0420 . Store associate recommended I use Cataclean to help clean out the cat, and to unplug the battery so it can reset the system. I drove about 20 miles or so & went to get retested, it unfortunately failed because the system wasn’t showing a proper driving cycle. He told me to give it 1-2 weeks to comeback for a retest, he said if there is no check engine light that’s usually a good indicator it will pass, but if it does, he said they do services where they clean the cat for about $600. Is that a fair deal? Or am I being suckered into something that won’t even benefit the car. I saw online for an aftermarket CA approved universal cat that would have to be cut/welded, part costs about $350. Labor, i’m not to sure, but i’m sure it’ll round about $600 total as well. What are you guy’s inputs on this? Thanks!

UPDATE: Welp spoke too soon, check engine light came back on as I took my car out to continue to flush out the cataclean. I feel like this has just been a never ending cycle that unfortunately is just going to break the bank. If anyone has suggestions, please let me know.