CEL / Error Code ... what do to?

[OrbeaRider]

Well, here's my problem: I started getting the CEL showing up some time back. I did a little research and it seemed like it was related to the O2 sensor so I didn't sweat it too much. I bought the 4Runner in Virginia, now live in California and have had no problems passing the smog check (the most recent one a few months ago ... after the CEL started to appear). Well, I finally was able to get the code sorted out and it is throwing back error P0420. I understand that this code relates to the CAT converter but it seems strange since the vehicle so recently passed smog. What else could be causing this? Is it a problem with the ECM (which I've read about) or O2 sensors? Any help would be appreciated as I just don

 

[drmorbius]

Well, here's my problem: I started getting the CEL showing up some time back. I did a little research and it seemed like it was related to the O2 sensor so I didn't sweat it too much. I bought the 4Runner in Virginia, now live in California and have had no problems passing the smog check (the most recent one a few months ago ... after the CEL started to appear). Well, I finally was able to get the code sorted out and it is throwing back error P0420. I understand that this code relates to the CAT converter but it seems strange since the vehicle so recently passed smog. What else could be causing this? Is it a problem with the ECM (which I've read about) or O2 sensors? Any help would be appreciated as I just don

 

[OrbeaRider]

Re: Re: CEL / Error Code ... what do to?

How many miles on your runner?

Sorry ... I meant to include that. I have a little over 90,000 miles and it is an 03 Sport V6.

 

[drmorbius]

Re: Re: Re: CEL / Error Code ... what do to?

Sorry ... I meant to include that. I have a little over 90,000 miles and it is an 03 Sport V6.

I was hoping it was still within the major emissions warranty period of 80,000 miles.

 

[toto]

That code pertains to the measured efficiency of the cat. The computer periodically messes with the fuel-air mixture to see if the sensors and the cat output react accordingly. While the cat could be the issue, a more likely cause is a sensor problem or possibly an exhaust leak.

 

[mybenje]

I have the same exact problem with my 04 4 Runner SE V8. It was diagnosed at 79K and when I went back to the dealer at 81K they won't look at it because at that time I did not know about the 80K emissions in CA.
I am in the process of filling a complaint with Toyota, because I don't have the resources to replace the cat for about $1500. I am not sure if replacing the o2 sensor will clear it or not? It will be interesting to know,,,