my sevice engine light turn on and i had the code check and it was P0421. i know it might be the cat converter or the o2 sensor. i got it reset and after three days the lght turn on again due to the fact that i havent changed anything. After one day it turn on the light turn off by itself.. what can this indicate. please help. im new to the forum

 

02 SENSOR I think DO NOT RESET IT Please. go to a mechanic or dealer have them reset it for you. If you have the money fix it right away after resetting

 

i did go to a mechanic shop to get it reset and thats how i know it was code P0241 Catalyst System Bank 1. it might be 02 sensor or cat converter. mechanic reset it for me and about 3 days it tur on again. after driving it for one day the light shuts off by itself and 2 days after it turns on again. Should i change the 02 Sensor or Cat Converter?

 

I have the same problem but mine was bank 1 sensor 3 and that's the one the cat.

yap go back to that mechanic and just replaced it. I am not sure which one but I know there are 3 sensors. You said Bank 1 but what sensor 1,2 or 3?

I'm not sure how much is the sensor but some of them will cost you $300.00 for the Good brand sensor and the cheapest is around $100.00
you only going to pay the mechanic $80.00 to put the sensor, just haggle.

or if you have the money just have a Engine Diagnostic all the problems will come out on the test inlcuding the sensors.

 

Well the computer only said Catalyst System Bank 1. It didnt say sensor 1 2 or 3. Thats why i dont know if i should change the Sensor or the Catalic Converter. I dont want to change something that shouldnt be change you know. Just want to make sure i change the right part.

 

doesnt anyone do a search?

theres a recall out for that.

 

but i bought it used and the car has 138K miles on it...would the dealer still do the recall?

 

not replace the converter.. but I think the reprogramming.
at the very least, pay them the small fee for it if its not free, cause the new cat will deteriorate at an accelerated rate if the software is not updated.

or drive it with a check engine light on.. which will cause you fail a smog test in a lotta cities.

 

so i can just take it to the dealer and ask them to reprogram the software? thanks man