Yet another P0420 code

I did contact my brother in law this morning, and he said he never had a CEL turn on when he had the truck. He also said he never had to replace any of the exhaust, o2 sensors, cats, or other emission equipment.

That means sometime after the truck got wrecked (back when he owned it), the year it sat without being started, and then me acquiring it the CEL came on.

 

Probably only that side.

Check the output on the other bank and see what it looks like.

 

Bank 1 system 2. This was also driving at 55mph while on cruise control.

 

Any possibility that it could be something else like a MAF sensor?

 

I'm trying to imagine how. IIRC, cat efficiency is determined at the ECU by comparing exhaust mixture before the cat, then comparing again after the cat, and calculating the % of difference meets a certain threshold (I have 13.x% stuck in my head, but I forget the exact amount and is that 13% difference, difference of what, eh?)

The threshold is too high/low the cat code sets. That being said, issues with the MAF mis-reading should lend to improper a/f mixture, that would lead to rich/lean exhaust, but the cat should technically still filter it? I suppose if it was hardcore rich or hardcore lean, maybe it would be less efficient at filtering the extra garbage, and that could cause it, but ... it seems unlikely, IMO.

One thing I hadn't thought of that's in the FSM for your year is possible exhaust leak. I expected to see faulty ECU in that list, but it appears not.

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Oh and here's the DI-300 page - is it possible you have an exhaust leak, maybe at the O2 sensor(s) themselves, or anywhere else that could be impactful?:

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I suppose it could be a leak, but there's all new OEM doughnut gaskets all around plus the Denso O2 sensors came with new gaskets. I guess there could be an exhaust manifold leak at the engine block (hopefully not!). I read that some guy stuck a shop vac in the tailpipe and turned it on to "blow". Then sprayed soapy water at all the joints. I think that might be next on the list. The more i look at aftermarket cats, the more they look like poo. The universal weld on that Magnaflow sells is waaaay shorter than the OEM. It has a 9'' body and a 13" overall length. So if i weld it in, i'll have to also weld in an extension piece too.

 

The plot thickens. I took my truck in for the warranty on the cats and when the shop ran their diagnostic reader, the only code it showed was p0340. I verified this with my scangiage before I left. Now I know for a fact it has been showing the two cat codes p0420/p0430 previous for like two years off and on. It was showing them just this last weekend still. I've never heard of the CEL changing codes like that before. So the muffler shop couldn't warranty the cats without the codes. I looked into the po340, camshaft position sensor. Looks like it's possible that my new DD injectors fixed the cat issues, but my mechanic had also done the TB/WP. So they have the truck again, in case they messed up the CPS.

 

Plot twist. Replaced the camshaft position sensor, cleared the code. CEL came back on for p0420 tonight. So now I'll wait for the p0430 to come back as well and go back to the muffler shop for new cats before my warranty expires.
I still don't understand why the p0420/430 codes disappeared after the p0340 came up.

 

I put the truck on my friend’s lift today. I pressurized the exhaust system with a shop vac (blowing in reverse). I then sprayed soapy water over all the joints. There was only a very faint leak in one spot in the driver side rear sensor seal flange. I contacted my friend who owns and exhaust shop about the leak. He told me that a stock system only has 3.5lbs of pressure. So to me, that tells me won’t worry about the slight leak.

Looking closer at the cats, and i’m beginning to think that they might be aftermarket? The exhaust system is from a 2000 4wd, while the truck itself is a 2004 2wd california spec. The two cats look VERY different from each other.

Here are pics of the truck. The blue arrow is where the slight leak is.

 

I can't help but think the California spec might mean the ECU has more strict parameters for the O2 sensors to check the cay function, hence different cats.

 

I haven’t bothered to research if the 49 state federal Tundras came with a different ECU than the California models.

 

They did. I’m 99% certain this is the case, when I was looking up an ECU for someone a few months back this came up, California spec was a different part number Hell if I can find the post now.

 

I made a plan today to swap in the 2004 left side 2wd cat and exhaust. The 2004 cat was REALLY oily inside from the engine burning SOOOO much oil. I’ve absolutely zero expectations that this cat will even work, but hey, i already have it. I sloshed around a gallon of gasoline inside the 2004 cat in order to clean some of the oil out of it. I then filled the cat with Purple Power cleaner to remove the gas residue. After i soaked it for about an hour, i drained the PP and thoroughly rinsed it with water.

When it came time to bolt up the 2004 2wd cat, i was confident that i was going going to be too short. So i was quite surprised when it bolted right up to the 2000 4wd exhaust system!

I fired up the truck and immediately white smoke was pumping out of the tailpipe. I kept the truck running for about 15 so that the exhaust could get good and hot so that it would burn out all the moisture. Apparently there was also still some oil residue in there as well, because it was pumping out smoke for about 10 minutes straight.

I reset the p0420 code. I’ll drive the truck around tomorrow and see if the check engine light pops back on. I can only assume that it will, but this is a no cost experiment.


This is the 2004 2wd cat




This is a pic of the cat out of my 2000 4wd truck. I’m now thinking that this IS an OEM cat.

 

Well, huh...i don’t even know what to think about that. Does this mean i should be on the lookout for a 2004 49 state federal ECU? It would probably cost less than california rated cats.


EDIT: Or better yet, can i just plug in the ECU that’s out of my 2000 truck? i’m guessing probably not since the throttle bodies are completely different?

 

I remembered reading about cleaning cats before and I never heard of using gasoline. So I found this info from: https://www.edmunds.com/car-maintenance/how-to-clean-a-catalytic-converter.html


Soaking: One method to try is submerging and soaking the catalytic converter in a soapy water solution. A dedicated oil or degreaser product will probably work best, though you might also try dish soap. Add your cleaner to a sufficiently large bucket of water where the converter can fit. Submerge the converter into the bucket and let it sit overnight. The next day, pull out the converter and ensure that the converter is free from any debris before letting it dry completely.

Chemical cleaning: For this method, try spraying a chemical cleaner (such as carburetor cleaner) through the interior of the catalytic converter to remove the clogging deposits.

Pressure washing: You can also try using a pressure washer to spray water through the inside of the cat to remove stubborn deposits, but make sure that the pressure washer's setting is at its lowest to avoid damage to the catalytic converter's internal structure.
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Yeah, i read all of those generic write ups more than a week ago. I didn’t see how a bottle of cat cleaner would ever clean the residue out of my cat. That’s why i cleaned it when it was removed. I used one of those inflatable rubber plumbing test balls to cap off the bottom of the cat. I totally plan on ordering a new cat tomorrow afternoon, but we shall see if i do...

 

I would think that this would be a decent thing to try since you plan on converting it to 4wd anyways. Althought it may not matter if the 4wd has it's own computer. But you may have to change the throttle bodies.
These are probably questions @empty_lord knows more about than most of us.

 

Disregard the gas tank stuff. I didn't mean to include that. I've used the gas tank shit and it didn't work. But I was talking about the soaking the cats in dawn and water overnight or pressure washing parts.

 

The reason I question the soaking in gas method is because unburnt fuel is listed as one reason cats get clogged

 

I agree. And that’s why i also soaked the cat in purple power for a few hours. After that i used a pressure washer to clean it (hopefully) the rest of the way.

 

I already converted the truck to 4wd a few months ago. I’m not sure which page i got around to the actual 4wd swap though... https://www.tundras.com/threads/tacoed-tundra-project.130491/

 

For some reason I thought you were still using the taco'd truck to haul logs

 

Nope, i’m 100% done using that truck...except for spare parts. Pretty much the very last day i finish splitting firewood, i split into the taco’d truck.

 

48 state. MA was the same as CA.

 

Just finished reading this thread. I've had a 0430, kinda of sporadic, nothing super consistent. Seems to stay away if I run her on the freeway just once a week.
But the reason I'm chiming in is looking at this OBD2 pic, does anyone else find it strange that the truck is in closed loop and the ECT is only 73deg????

 

I’d think that out of normal range? I’d expect you to pop P0125 or similar if the ECU felt it was out of range though. if I recall from @Tundra2’s experience, truck can’t enter closed loop without properly functioning O2 sensors. In his case, he had a bad ground somewhere on the O2 harnesses, though I dunno (or don’t remember) if his mechanic guy ever gave the skinny on exactly where it was.

 

Actually wait… brain just kicked in. How would you enter closed loop if it was actually that low. Huh. Whoosh. Time to dig into the caffeine and get my ass off this computer for a few. What does the dash gauge say the temp is? Two different sensors in your truck, one for the gauge, one for ECU. I assume the scanner is using ECU sender.

 

Yeah I thought that was a "key" parameter the ECU looked for when making the call to go closed loop and start listening to all sensor inputs

 

Indeed, I saw "73" but registered "173" in my brain. That is super fishy. But I'd expect other things to be squirrely if it was really that low? Does the reader support 3-digit output?

I wonder how much the ECU temp sensor costs for your truck?