Catalytic Converters code PO420/430

Hi, hopefully someone can give me some more information about this.

Yesterday, the Check Engine light turned on for my 98 Lexus ES300. So I brought it to the dealer to check. They told me the Catalytic converters need to be replaced, and it's going to cost $1648.35!!!

And he told me there're two converters, one costs about $250, the other one costs about $1100. I should have asked him why the other one cost much more.

My question is: what's the cause of bad catalytic converters? Is it just because of the high mileage? My car has 116K on it, but it runs great and has never given me any problems. I had an accident early this year which has impacted the front hood, I'm not sure if it also impacted the converters? Is it possible?

Thanks a lot for your help!
Emily

Take the car somewhere like an autoparts store & have the codes scanned so you actually know what the problem is, not what people tell you.

Normally running too rich, or using gasoline additives will destroy cats.
The main cat is 50-300 to buy one & have it put in, the pre-cats on the y-pipe mean you either rplace the y-pipe, or have new ones welded in place.



And no, it's not going to cost you that much to replace them if they are bad.
You can have a custom performance y-pipe made up for say 250-300 and gain 10-15bhp. Then have a new higher flow generic main cat welded in for another $100.