Yet another P0420 and P0430 problem

Yes, another thread about these codes, yes I did search this forum for this subject, yes I’m still asking y’all lol

Anyways I’ve been driving on these codes for quite some time now with no loss in performance or MPGs. My oil and coolant levels are normal. OEM exhaust system. No signs of soot and no audible leaks (still want to do further testing with that). The pipes are 100-150 degrees hotter before the cats vs after them. But my ODBII scanner is reading a pretty choppy wavelength for both banks and both sensors.

Bad sensors or bad cats?

Trucks a 2006 V6 with 137k miles.

 

It's probably bad cats but who wants to replace those? I'm sure not looking forward to it. I get the P0420 code from time to time.

Cataclean, Duralast, and Lucas are the things I've tried. I only use name brand gas now. I haven't had that code for a while now but I'm kinda sure it'll come back any day. I did get in a small wreck and i'm just now starting to drive it again, been a year out of commission. Not sure if unhooking the battery for an extended period reset my computer but I'm lucky for now.

Also I made the 02 sensor foulers but my 02 sensors are seized so I still haven't gotten to go that route.

Good Luck!

 

Yeah this is definitely one of the pain in the ass codes to diagnose lol good luck with you too!

 

A month ago My.06 just got one after 200k. I put a tank of premium in and it went away after 25 or so miles. So now I'm stuck putting premium in so the code wont come back, so that's why a week ago I put a supercharger on just to not waste it lol.

Real talk though, I saw on a thread here that premium chases away the codes.and they were right. $200 O2 sensors are much cheaper then cats,and labor wise you could do the sensors yourself without splicing in a new 800$ replacement cat

 

Your cats are indeed the problem. Honestly those two codes are one of the few codes that you can the vast vast vast majority of the time take with no salt.

Proper diag though is to compare upstream and downstream O2 sensors to each other for each bank with the engine warmed up and idling. Upstream should look like a sine wave or in other words it should fluctuate constantly. The downstream should be consistent and pretty well flat. If the down stream follows the upstream then that shows that the catalyst is not converting.

With an infrared temp gun the outlet(backside) of the cat should be warmer than the inlet(engine closer side). Sounds like you've also checked that and it's shown your cats to be defective.

When you replace them just verify nothing abnormal is being combusted, such as coolant, excess oil, excess gas, etc. cats do wear out but it's important to check that it wasn't poisoned by an abnormal condition like mentioned above. If you don't find and correct the source of abnormal combustion you'll be changing your cats again shortly.

Cats often stop converting, throwing this code without noticeably impacting engine performance. Primarily emissions

 

I hate to say I think you’re right…I really just don’t have the $$$ to fork out for new cats. Thanks for the write up!

Also, which cats need replaced, the ones on the headers or the downstream ones? Or all of them lol

 

I guess I could try and run through a tank of premium, but after reading the post below yours I feel like the problem is much larger

 

I don't like to be the bearer of bad news but I'd rather be honest... if you can live with the light for a while and you're not burning anything abnormal then no damage will be caused to your engine.

 

My 06 v6 has been getting these codes since 280k miles. It would come and go until months ago i did the fouler trick and 2k miles later, no dash/obd code.

 

Is the fouler the spacer for the o2 sensor?

 

Yes, here's the discussion
https://www.tacomaworld.com/threads/0430-and-0420-code-hell-d-fixed.406596/

 

I’ll check it out. I do realize this doesn’t fix the cat but I’m sure it’s nice to get rid of the code until it can be fixed!

 

oh yeaah definitely, i'm in california so either get new cats or find a way to mickey mouse it and i did and it passed smog!

 

Foulers do work... up to a certain year. I'm not sure on the year but at a certain point they updated the obo testing to randomly richen or lean the engine for an extended moment to see that the downstream sensor responds accordingly. This was purposely to counter against spark plug foulers. However give it a try to temporarily deal with the light. Based on Thunderball's experience you should also be good to go

 

Mine has non oe cats. Po420/430 was common pre foulers. Never happens anymore.

 

Have you checked your seals for leaks? Check your headers, collector, and y-pipe for leaks. Use soapy water and check for bubbles forming. You might also have leaks around the Heated O2 sensors, pre or post cat. The fact that you're getting both at the same time leads me to believe that it may be with your y-pipe.

If you determine that you don't have any leaks in the aforementioned areas, I'd rent a borescope and remove the 02 sensors and check the rear face of the cat. Check the condition of the fins and baffles. If it looks like a grenade went off, then your cats are shot. The spark plug non-foulers are Band-Aids and if your state conducts visual inspection, it likely wont pass.

-J

 

Maybe I'm the only one that ever has been or will be this lucky, but (as I've posted before) when this happened to me...I went to the online recall database, entered my VIN, found that my recently purchased used 2012 was subject to a recall for poor cat performance that had never been addressed, and was able to schedule an appointment at the dealer to have ALL of my cats replaced free-of-charge.

https://www.toyota.com/recall

I cannot be the only one that bought a used truck with bad cats that hadn't been taken in for the recall.

 

Dang I didn’t know this existed, but I just put in my info and it said there’s no open safety recalls for my vehicle. Worth a shot tho, thank you!

 

I have an '06 w/ 145K and the 420/430 started at about 110K about once a month until this last year when it started happening more frequently. I can monitor my OBD from the stereo and the AF sits at 14.5~14.6 all the time and the mileage hasn't changed enough that I can tell anything is different and it still runs great, I just got back from a 2000mi trip. I just stumbled across this and ordered some plug anti-fowlers, to try out.

I've read sandman's writeup on the Fuel Pressure connection to these codes and would like to test that also. Can anyone indicate where the easiest place to tap in is at? I have both a dead end FPG and an in-line FPG. Ideally I'll just add a inline coupler in a section of rubber fuel line as a place to tap in. A TW link to the FP Test procedure would be greatly appreciated if anyone has it.

 

My P0420 came back today.

Replaced the PCV Valve and cleared the code. The engine is running way better/smoother. Mine was pretty dirty and I think it was so bad it was causing problems. We'll see how it goes.