0430 and 0420 code hell. :D FIXED!

Posting here simply because I searched here a ton when looking for a fix and found lots of good dirt..... this is the fix I did, with great success. This fix should probably be tried first, before cats are changed, just to see if it works. Hope I am not being a pain in the ass. Its early and I am only on my first coffee/beer.

I have been through hell and back with 0430 and 0420 codes and have figured out what I needed to do...quite the learning curve.
First, I went to a reputable aftermarket cat. cost about $450 Canadian for the two...a hell of a lot cheaper that Toyotas. I e-tested. Failed.
Then bought all 4 o2 sensors. E-tested. failed. Then I researched the living crap out of everything, went to my Toyota dealer to ask their thoughts and learned a few things.
Using these figures as mythical ones merely for illustration...but hopefully the point will get across.

Toyota Cats....90-95% efficient.
Aftermarket Cats....80-85% efficient.

The difference is enough to send the Toyota ECM into fits, spurting out codes of cat failure.

So, amazingly enough, Toyota gave me the same fix I read about elsewhere.


SPARK PLUG ANTIFOULERS. $6.00 (18mm, I believe)

Take the antifouler and bore it out to a minimum of 1/2".....uninstall the downstream o2 sensor, reinstall the o2 sensor into the anifouler, then screw the assembly into the o2 bung....tighten, no silicone, just the supplied crush washers....reset everything, go through a complete drive cycle and baddaboom! CODES GONE!

This took me a month of resetting, waiting for parts, installing and CRAP. The worst is going through drive-cycles...time consuming.

DO NOT bore less than 1/2". It WILL set off the code again. Also...if for some strange reason this doesn't work...do not panic...STACK two antifoulers!!

I really hope this saves a bit of time and worry for some...I live in an emission tested area and it sucks when you can't get those codes gone!


now...amusingly enough, I am about to go to the garage and bore out another set for my buddy with the same issue.

 

I thought I knew everything - this is so embarrassing - what is anifouler ?? Where is it ?? Pics would be great - I googled anifouler and found stuff for boats. Again Pics would be great. Thanks for any help.

 

Don't feel bad....kinda made me think of muffler bearings.... I will take a few before and after pics in an hour or so and post them here. Gotta go get a new reamer.

 

Here is my collection haha. It's basically just a spacer for the o2 sensors. They also make them with 90° bends for tight places. Worked like a charm on my Lexus with Invidia mid-pipe.

 

Used these on oil-burners years ago.

 

Any more detail on the boring? Do all brands need boring?

 

Lol....the help ones are one's I had picked up. I'm pretty sure they all need to be bored out. As spark plug anti fouler they require a much smaller hole. attached is a picture of before and after they are bored 1/2 inch.
Crap. On my phone. One sec.

 

I could fricking paint this picture and mail it faster than I can figure out how to post it...

 

Thanks for the information Jaab ! I'm not having any issues but this is good to know, however my dad is with his Camry. I've changed both of his sensors and turned the light of for awhile but it comes back on, I'll try this.
Thanks for your diligence.

 

This is still just fooling the computer into thinking you fixed the problem. Check your fuel pressure.

Even now check your fuel pressure and compare it to what is called for. I battled with this issue and fixed it correctly. The o2 readings are just a consequence of the real problem and the anti foulers are just masking that.

 

@Sandman, what solved your issue, new fuel pump ?

 

Yes....but if the only thing being fooled is the ecm into thinking it has the ultra-efficient toyota cat....well, I am OK with that.

 

There are tons of potentials that would lead to these codes...this fixed mine. And my truck gets great mileage and has perfect power.
This worked for me....all I'm saying

 

Thanks for your reply and work. Glad it wasn't lumped in with a muffler bearing or a flux capacitor. As an aside - one time I had one of those chain muffler shops change a o2 sensor and then had to have a real mechanic change it again later on. This info might come in handy and save $$. Thanks again.

 

Yes... IF..

That's great but the problem is NOT fixed . Check your fuel pressure and we can compare real numbers. You have merely bypassed a symptom.

 

I desperately urge anyone with this issue to check their fuel pressure before applying a blind solution. It's an inexpensive, quick, and easy diagnostic tool. #themoreyouknow

 

Correct, URD USA walbro255 plus I added an in line filter.

 

Check here to see what all I went through, and my solution, not coverup..
https://www.tacomaworld.com/threads...ng-searching-when-accelerating-uphill.311561/

 

Interesting. A bad fuel pump is creating bad cat converter issues for people, it doesn't surprise me because you are essentially making the engine run overly lean due to the lack of fuel being supplied to the engine. In the same respect it doesn't surprise me because if you guys who have never done the fuel pump on these trucks before have ever seen what it looks like before, it's ridiculously small. Like so much to the point where I am surprised it is able to keep up with the demands of the engine in general. My 2012's pump failed in less than 50K just to give you an idea of how bad these are. Made by Denso at that. I don't know where they went wrong with these.

 

For reference