P0420 pending?

Well I stand corrected. I went under the truck after I got it finished, tested it the way he said by taking a vacuum and putting it in the tailpipe blowing with no leaks. I went out there again this morning and did the same thing, sure enough both connection points are leaking, I can feel the air coming out of both of them. I used factory oem toyota gaskets and everything. This has to be the culprit right?
Follow up question to that, I have always had a hell of a time getting these to seal up properly, can i use permatex copper rtv with the gaskets to try and seal this up? I don't know what else to do besides that if anyone has advice for that... thanks

 

I just noticed the flanges are not straight and are bent. Would it be advisable to cutting out the original 2 bolt flanges and going to a 3 bolt flange?

 

Would something like this be better? I'm tired of dealing with these factory connections. I can weld so welding these in aren't a issue.

$29 FGJQEFG Exhaust Flange Bolts Quick Fix Repair Pipe Kit w/Gasket & Hardware, 2.25'' Inch ID 3 Bolts T304 Stainless Steel Universal Flange Replacement Kit

https://www.amazon.com/FGJQEFG-Hard...ocphy=9015255&hvtargid=pla-1932488526682&th=1

 

B1S1 (bank 1 sensor 1) is the sensor that the PCM uses for making adjustments to just about everything. B1S2 (bank 1 sensor 2) is the after the cat sensor. B1S1 graphed pattern will be a ragged saw tooth pattern. B1S2 should be a smoother low amplitude wave. If B1S2 almost mimics B1S1 then the cats are either not hot enough or are worn out. A catalytic convertor is nothing more than a sophisticated oxygen storage device, if the sensors measure the same amount of O2 going in and coming out. Converting the gases consumes O2. You should be able to clear the pending by resetting the PCM and running all the monitors. The aftermarket cat manufacturer's dont put much of the material that does the actual chemical conversion to keep the prices down but then they dont last as long as a factory cat.

 

Check for exhaust leaks.

 

Couple messages ago I stated I found the lower 2 gaskets are leaking due to bent flanges. Will be replacing those and going from there. Manifold is not cracked nor the upper 2 small gaskets are not leaking, just the lowers in-between the 2 cats and the cat and rear 02 sensor

 

I was getting the same error message. I thought maybe it was the cat or 02 sensor. It was neither, it was just an exhaust leak.

 

I'm not sure what good alternatives there are to help you seal up those flanges. I tried JB Weld and that stuff falls right off. Might be a good idea to try that other stuff you mentioned as a quick and cheap check. Could work. Better to just weld them straight together and eliminate the flanges altogether. That's how mine are set up for both sides of the rear cat (probably aftermarket). Not my choice just to have it that way its just the way it came and then recently rusted apart. Had my neighbor do a shit job repairing (weld next to the cat) and then got a mechanic to replace the pipe but miss the shit weld. It was my neighbors weld that was leaking. Finally found the right exhaust guy and he buttoned things up. Three exhaust guys to repair hardly anything. 300 miles later still no 420 code. Which in my experience comes back real quick after clearing the code.

 

I have been dealing with a P0420 code for over a year on 97 Taco 2wd xtra cab 2.4L 5speed with 168000 miles. using advice from various Taco forums have replaced EGR valve and module, most of all vacuum lines, cleaned MAF, few months ago moved attention out from under hood to exhaust, 2 cans cat clean. priced a oem converter from Taco Stealer ship part only $1700.00 + not a chance in H&ll, ordered this part from China BINGO!! CEL went out right away, been 2 weeks seems good to go.

 

That does the same thing as the oil fouler inserts from days gone by… it is out of the exhaust stream enough to fool the PCM. Are you in a smog state, if so and the smog guy catches it…they will flag you to the state, and that aint good. If questioned plead ignorance.

 

Good afternoon gentlemen, it has been some time and I hope to receive more advice from here. I crawled under my truck to check for leaks (I think I talked about this, not sure but I'll restate it anyways for backstory) and sure enough both connectors under the truck were bent to hell (probably from me, I have a tendency of over tightening things) and were dumping out exhaust, I said to hell with the factory connectors as I have always had problems with them and could never get them to seal so I welded in 3 bolt flanges to my exhaust, rechecked for leaks and had 0 exhaust leaks. Problem solved right? Wrong. I learned there was a drive procedure for these tacomas that I was trying to follow when halfway through I hooked up my scanner to see if I was getting anywhere and my Cat was green and nit blinking red, only to see I had the P0420 code pending pop back up!! Not what I wanted to see... so far I have replaced the cats with magnaflow cats that were speced for the 1st gen with a 2.7, both 02 sensors with factory denso sensors, got rid of the crappy factory connectors and welded in 3 bolt connectors for a better seal, and if it matters I have a Flowmaster FX muffler even though I don't think it matters but I will throw that out there anyways if that helps for reference. Again I'm 100% positive I have no exhaust leaks now and I have good parts that I have installed onto it but to no avail. Is there any other things that could go bad to throw the P0420 code that I need to work on? In my county in Ohio I have to have a E-check and my plates are almost expired. I'm not sure where to go from here and I'm running out of patience with my truck. Any further advice would be greatly appreciated... thanks again
Matt

 

The spacer shown above or a spark plug anti fouler installed just might space the rear O2 sensor far enough away to fool the PCM, will it fool the inspector, depends on how hard he looks.

 

Clear the system by pulling the positive battery wire for 10 seconds. Pending code should be gone. Drive until the OBDII emissions readiness checks are all Complete/Ready (might take a tank of gas).

 

You tried a new rear sensor yet? (idc if they say they tested good)

 

Yes I just replaced both sensors no more than 2500 miles ago. If that

 

I was told this was not good to do, I have a code reader that clears codes and reads basics, I've been clearing the codes and they go away for a bit but always comes back

 

No harm, just has to relearn fuel trims too. But same outcome as clearing codes.
I can't fathom why a catalyst code would be pending unless it is triggered intermittently...meaning the trigger is during your drive cycle. Post some pics?

 

According to this....the only thing you havent checked....is an intake leak....

P0420 Code: Meaning, Causes & How To Fix It (Full Guide) (mechanicbase.com)

if you scroll down to the toyota part....its says even bad piston rings can create a lean condition...

How many miles?

 

My truck has 226,000 miles on it. I'm praying it's not the piston rings, I don't feel like yanking my entire motor out of my truck lol. I'm gonna have to go through and check everything, otherwise I may have to have someone with a better diagnostic tool or dealer inspect it.

 

There's no way its piston rings at that milage.....unless something extraordinary has happened....

unless you had one of those 2nd gen 2.4's oil burners with the bad rings...

1st gens are weak on HP....but extreme long life...