P0420/P0430 Codes.

I have a 2005 Tacoma 4.0L engine with 230,000 miles. I got both a P0420 and P0430 codes. I replaced all 4 O2 sensors with high quality Denso sensors and the code persists. I have no air leaks from exhaust. I am starting to think I need to replace my Catalytic converters.

Is it worth trying to clean out the Cats somehow? Is 230k miles usually when the cats get clogged?

 

Long term fuel trims. 11.7 and 11.7

Short term fuel trim. 3.9 and 3.1

 

Are my O2 sensors reading at appropriate volts?

I am getting 15mpg.

 

Ideally, you'd want to graph the A/F and O2 data.
If you're scanner can do that, you can sufficiently diagnose the converters yourself.

If you want to learn how. Watch the video below. The guy in the video is an Expert Tech and teacher in an Automotive school.
https://www.youtube.com/watch?v=vyVnhCIMDnw

 

9 times out of 10 those codes mean the converters are no longer functioning as intended.

Those codes don't mean the conver is plugged, they set when oxygen storage capacity of the converter is low.
Now one or more could be plugged or restricted as well but a plugged/restricted converter won't set P0420/430 codes nor do P0420/430 codes mean a converter is plugged.

There are some additives that "might" temporarily restore a marginal catalyst enough for it to pass the P0420/430 codes for a bit but the only real fix is to replace them or live with the light.

The fuel trims while a bit elevated aren't too concerning, MAF reading is slightly low if that's at a hot idle which could account for the elevated fuel trims. Do you have an aftermarket air intake installed?

 

Mine started throwing the codes at 80k and dealer would not warrantee them when i brought it in at 130k. Used cataclean and just kept resetting every 5k-7k. Replaced both cats, one at 190k and the other at 215k. Turns out the head gasket was blown, and I had them replaced at 240k. I think this was my problem the entire time starting at 80k(did not idle well from 80k). The head gasket symptoms did not get bad until about 238k with misfiring and bucking on the freeway.

 

I’ll get my hands on a better scanner and try to graph it soon.

Those stats are at a hot idle. And I have stock intake and regular paper filter just replaced.

 

Took off my whole exhaust system and cleaned out all 4 cats with multiple different cleaners and flushed them out. Not much contaminants. Code still came on.