How many catalytic converters does a 2005 Kia optima 4 cylinder engine have

Question

I have a p0420 code on my 2005 Kia optima. Want 2 change the catalytic converter and the rear O2 sensor. Is there a front and rear cat, and should I change both 02 sensors

Answer 1

P0420 Catalsyt system efficiency below threshold

You have two catalytic convertor there the MCC and the UCC, The MCC is what is nicknamed the mini catalytic convertor ,or better known as the warm up catalytst. The code you have is  for the UCC or the catalytic convertor. Should you replace both 02 sensor there is no need to , what you should do is check for tune up, worn sparkplug can lean out the fuel system so check for tune up , a good airfilter,

 Here what I call a grave yard of catalytic convertors. Its a early grave yard . Most of these owner are dedicated to maintaining their vehicles. which is good., tune up the engine , change oil on a religous schedule, and that all good. But what worn the catalytic so fast? the Motor Oil. If the vehicle does not call for full synthetic motor DO NOT USE it.