What causes catalytic converter to go bad? on 2001 Dodge Neon

Check engine light is on & the computer code indicates this

Asked by for the 2001 Dodge Neon
Could also be due to engine running too rich, burning oil, or an internal coolant leak.
1 more answer , 5 more comments
Any other codes besides P0420? mileage and maintainence have alot to do with failures. And yes as stated prior , to rich or to lean or misfire conditions all contribute to premature failure. Also the code may be set falsley due to other conditions. should have it monitored for function before replacement.,,,,,,,,,,,,<<<<<<<<<<<<< UNIONDALE H.S. class of 1980 >>>>>>>>>>>>>>>we rocked!
Yep.Long Island. Escaped in '86
Thought you was a yank. I bet them was rocking times sho nuf. Was here in 74 too.
GOOD OL DAYS! I just didn't know it at that time.
Wonder if 'kthgran' is ever going to answer my questions , or were they just stupid questions?
We get a bunch of that. I think if one ask a question and gets an answer, it should
be acknowledged.