OBD Code P0421

What do you all think - My daughter came home with a check engine light. Ran it up at AutoZone and got a P0421. Reset was successful!
 
 

Thats emissions, more specifically catalytic converter.
 
Minor, and if the car has near 100k miles, thats about right for it to be replaced anyways. Me thinks your daughter was driving a little enthusiastically at the time

Would you believe 220K miles
 
Never had it changed - Question estimate of cost?
 

Depending on if you like to be dealer raped. You do it yourself, will cost you about 150 bucks depending where you get it. An OEM catalytic converter is about 350 last time I looked. The advantage of that, is a warrenty.
 
Holy hell 220k!

sebba, catch me if i am wrong..but doesnt 3gs have like four cats? i guess it would be the final cat right?


anyways, if you dont want to do it yourself...muffler shop will do it fairly cheap and quick

Who the hell knows what one it is.
 
But yes, a muffler shop will do it for a lot less.

Po421 is warm up cataylst below threshold bank 1.  So I would get the cat replaced on bank one.  If there are 4 cats only replace the one monitored by the 02 sensors.