Po420 code. Need help!

[Homegrown-Yota]

CEL came on. Po420 on my 99 t4r. 234k. Iv already replaced both 02 censors several months back do to other problems.
Does that narrow it down to it being my actual cat needed replacement? And I'm pretty sure there are 2 cats arnt there?

 

[downpour11]

This thread should help: http://www.toyota-4runner.org/3rd-gen-t4rs/97474-p0420.html

Look under your truck, are there 2 cats or 1?

 

[fish0281]

CEL came on. Po420 on my 99 t4r. 234k. Iv already replaced both 02 censors several months back do to other problems.
Does that narrow it down to it being my actual cat needed replacement? And I'm pretty sure there are 2 cats arnt there?

I'm confident that it is in fact your CC that's bad. I don't think the sensors are wrong as often as we hope they are, and it doesn't really leave any other possibilities if you've replaced them.

 

[Homegrown-Yota]

I'm confident that it is in fact your CC that's bad. I don't think the sensors are wrong as often as we hope they are, and it doesn't really leave any other possibilities if you've replaced them.

I'm thinking so too. And I checked and it Looks like 2 cats. Cuz they are both between both 02 censors.
So how do I know which one to replace?

 

[fish0281]

I'm thinking so too. And I checked and it Looks like 2 cats. Cuz they are both between both 02 censors.
So how do I know which one to replace?

The front one sees the most action, but if it's gone bad, there is a high likelihood that it has passed along a bunch of crap to the second one and is slowly but surely plugging that one up. I just recently replaced mine and put a thread up here, check out the last pic I shared... mine was TOAST!

That being said, I see you're in CA and there are only very specific CCs that they deem acceptable (and will pass emissions).Here is a link. I think the law there says that you will need to maintain the factory configuration, so you won't be able to go replace both with a single universal CC as some may suggest (nor would I expect that to work, at least not very long).

What kind of fuel mileage are you getting? That can be a tell-tale sign of a bad CC...

 

[Homegrown-Yota]

I'm not getting nearly as good as mileage as my previous t4rs with 3.4. Or as much as I was first getting with my runner now. Seems to be slowly going down.
So that says pretty plainly bad cat I guess?

Guess il be looking for a new one. I really don't have the money to be putting a factory replacement back one.

 

[fish0281]

Yeah, I agree. When the price of the part is a significant portion of the truck's value, it's just not worth it. There are definitely some cheaper aftermarket options out there, but probably on the order of $600 in parts and their longevity is questionable (1-2 years?). I think that database does list some universal CCs that you can get cheaper, but then you have to get them welded in too...

I have not calculated my fuel mileage yet since replacing mine, but the engine definitely seems to be breathing easier.

Good luck with it, it's a tough problem to have!

 

[Homegrown-Yota]

Yeah, I agree. When the price of the part is a significant portion of the truck's value, it's just not worth it. There are definitely some cheaper aftermarket options out there, but probably on the order of $600 in parts and their longevity is questionable (1-2 years?). I think that database does list some universal CCs that you can get cheaper, but then you have to get them welded in too...

I have not calculated my fuel mileage yet since replacing mine, but the engine definitely seems to be breathing easier.

Good luck with it, it's a tough problem to have!

I'm not worried about the Welding part. I work at a welding shop...haha. But yea I got the truck for $3600. I'm not even close to about to pay upwards of 6-900 on new cats. Your info has been really helpful. Thank you. Il go check on some aftermarket universal cats. And I'm buddies with most smog guys around my area. So I'm sure I can pull the "tip the smog guy" trip like lost guys on here say I do with universal cats.

 

[fish0281]

I'm not worried about the Welding part. I work at a welding shop...haha. But yea I got the truck for $3600. I'm not even close to about to pay upwards of 6-900 on new cats. Your info has been really helpful. Thank you. Il go check on some aftermarket universal cats. And I'm buddies with most smog guys around my area. So I'm sure I can pull the "tip the smog guy" trip like lost guys on here say I do with universal cats.

Cool, that all works! There's also a company (URD) that sells a thing that modifies the O2 sensor signal to trick the ECU into thinking the exhaust is up to snuff (no pun intended). That'll at least get the CEL off.