Which Catalytic Converter?

2003 Pre-Runner, 2.7L, Auto, 295,000 miles

Got a CEL, scan showed P0420, catalytic converter. I tried CataClean in the gas, but it worked as well as I expected. As in, didn't work (you can't blame me for trying). Not wanting to play diagnoses-by-part-replacement, I'm wondering if any of you, particularly techs, have had this issue, and which converter was it? Looking for consensus

Thanks!

 

Did you verify it isn't a sensor failure? Pre CAT exhaust leaks can also cause that code.

 

Well, the upstream O2 sensor isn't too old. I have no indication of an exhaust leak. I did have a bad misfire for a few days (only on hot starts - weird) before I got the injectors rebuilt, and that makes me think that might have been the final nail in the coffin for the cat...

 

Just saying, no use in throwing a new cat at it if there are other, cheaper causes. And not sure what your reference to the upstream sensor has to do with this.

 

yup, but what do I know...

 

Take it off and checked the comb? Majority of the issue is exhaust leak as stated

I tagged you

 

What sensor were you referring to earlier?

 

The p0420 code is coming from the downstream O2 sensor. The one after the CAT. Either that sensor has failed or is failing to report good info to the truck's ECU.

 

Yeah, okay, makes sense. Wonder when I replaced that last...

 

bad info....
either 02 sensor can fail, the front 02 or the rear cat monitor sensor....
the front 02 sensors switches rapidly....
If the rear cat monitor sensor switches rapidly too, that indicates the front or both cats are bad.
The cat monitor sensor is suppose to be a more steady voltage signal than the front sensor when everything is operating as it should.

Ive never seen an exhaust leak cause a p0420, regardless what "the book" might say.....
Atleast not on any ford, & the trucks are notorious for exhaust leaks....

 

So, summing up what you said here, I have a bad cat, if not both.

 

im not a toyota tech.....
Never touched one....
But been an engine, exhaust, drivability, performance, tech for ford for 32 years...
The system operates the same...
I diagnose bad cats, its what I do....

If Toyotas are one off & the very slightest exhaust leak will cause a p0420 or p0430, I wouldnt know...
Open your hood & have someone cold start it & power brake it while its cold while you have your ears under the hood & in the fender well......
If you dont here a tick tick tick that sounds like an exhaust leak....
You truly eliminated the possible exh leak.

You want to parts cannon 2 new sensors at it to kick the can down the road, so be it...

Guys on these forums feel a slight misfire wont cause a cat to go bad, as they continue to drive their trucks while it runs like shit...

Where I come from, we diagnose bad cats looking at all the appropriate data, you dont have that luxury...
02 & cat monitor sensor voltage switching
cat converter 02% saturation
fuel trims
etc, etc...

 

Eliminate all exhaust leaks first. The cheapest way is to take a shop vacuum and put the hose on the exhaust port of the vacuum and tape/seal it to the exhaust pipe on the truck then crawl under the truck with some bubble making mixture in a spray bottle... any leak, even a little one will make lots of bubbles.

There is also a work around if it is the cat... you modify the wiring going from the rear O2 sensor with a few dollars of electrical bits. This is a emmission defeat modification and if caught, big time fines. Somewhere in this forum is the post.

 

If you have more than one cat only the upstream one is monitored.
95% of the time P0420/430 is a cat that is no longer functioning as it should.

IMO it's a 22 year old truck with nearly 300k on it, if your not in an emissions testing area and the converter isn't plugged stick a spacer under the downstream O2 sensor and run it or live with the light.

 

That's the issue - I'm in CA, the king of emissions testing. I'm going to have to do the work, just trying to get the best idea for what needs to be done.

 

Im in San Diego...
Seen many vehicles with an anti fouler installed at the sensor to get light to stay off pass the sniff test regardless that the cat is no longer "efficient"
The truck will still burn clean as long as its not doing something stupid like burning a bunch of oil....

 

b4 i shelled out $$$ on CAT
i would def try these 2 methods first

https://youtu.be/5icTmYItwiE?si=TkaecAFmzwjRtAAZ

 

Scotty Kilmer is an idiot....

 

Scotty is an idiot....
The OP already tried some snake-oil already which im sure has lacquer thinner in it which is suggested in the video you posted.
The OP stated, that didnt work....

 

I'll vouch for the exhaust leaks at first sensor or in between first and 2nd sensor will cause a P0420 code. Lived it and fixed it with a weld.