P0421

bluelancer20028 · Jul 11, 2009, 10:16 PM

I got this code that keeps coming up and i figure its the o2 sensor. Anyone have any insight on the code?

darkmitsu · Jul 15, 2009, 09:06 PM

DO your research before posting Code P0421- Call Mitsu before you do anything!

bluelancer20028 · Jul 15, 2009, 09:18 PM

yea i found it didnt think before i posted

lancerguy0208 · Jul 27, 2009, 09:29 AM

I just got that same code a few days ago and I was about to post and ask what I could do about it. I scanned it and it means your warm up catalyst is not right. In other words, your air/fuel ratio is a little off. I changed my air filter but the light didnt go away. I need to know what else the problem might be and what else I can do to get my A/F adjusted.

lancerguy0208 · Sep 7, 2009, 01:31 PM

It was a factory recall. Does anyone have a copy of the customer notification letter sent out by Mitsubishi to all the owners who have this code?

Ketchup2me · Sep 24, 2009, 10:45 PM

Hey i bought my car with 76k and i swear around 80k my CEL came on with the p0421 code. i have the obd 2 scanner so i've memorized this code by now. It never affected anything but now i have 96k miles and i'm due for a inspection sticker soon.

If i replace the speedometer and drive til i get about a 78k reading will the dealer change my cat for free? I did a carfax and my last known registration calls for 76k miles. I know it sounds a bit fishy but hey, not my fault my cat went bad.

You think that will work? i dont see why not