Dreaded P0420 CEL UPDATED post #59

The truck tunes itself driving down the road! You are not going to be able to "piggy-back" any software that will satisfy what the pcm is looking for to satisfy cat monitor

 

Cheap cats are cheap because they put a bare minimum amount of palladium,rhodium,etc (these metals are expensive, that's why people steal cats) in the cat. Factory cats are expensive because they can function correctly during all operating environments

 

Aftermarket cats aren't necessarily the issue. Correct they may have less "magic" in them but they are built to a standard which the company (hopefully) stands behind.

 

I would think that the seller is responsible for having the vehicle "smogable". That is the law in CA.

 

The oems stand behind their cats till 8 /80k. They have to..

YOU GET WHAT YOU PAY FOR..

 

I understand everybody on here is trying to help but if this kid actually wants to fix the problem he needs a new cat everything else is just a waste of time and money

 

Normally that's true. I bought the vehicle in Vermont and it has a Vermont inspection sticker on it. However I live in NY. This requires that I register and get it inspected in NY. Also it's a 2002 with 107,000 miles on it. No warranty. Decent seller and he was very upfront. The CEL came in during my drove home with it.

 

If there is a real problem (exhaust leak, etc) it doesn't matter what CAT is on it. I just replaced a leaking exhaust donut on mine and it was throwing a p0420 code, code gone. I guess I wasted $15 and the 10 mins to check for an exhaust leak.

 

it doesn't look like he replaced the frame :-(

it may not be too late to make that happen

 

The seller knew it needed a cat, that is why they put one on it. They cleared the CEL and on the drive home you went throught the "drive cycle" and the convertor efficency fault was triggered. A longer test drive might have revealed this. Call the seller and see if they will meet you half way on getting this resolved.

 

I agree, but first he should do the free things he can do himself to see if he can find a problem. Then take a price on the fix to the seller.

 

My wife's car was throwing the lean left bank code intermittently and turns out it was a hole in the boot between the MAF and the intake.

 

Also I replaced a cat on my last car but didn't replace the 02 sensors... Code came back

Turns out both needed to be replaced. So I did. No problem after that, although I sold it, so who knows.

 

There's a sticky thread at the top of the 1st gen forum all about the 420 code.
https://www.tacomaworld.com/threads/addressing-some-common-misnomers-of-the-p0420-code.396763/

 

I'm taking everyone's input into consideration. As mentioned, I'll do the easy/free stuff first. Then onto maintenance items since some need doing anyways.

I own a paintshop so some days are busier than others. Frame recall was done about 4 years ago. Timing belt was changed at 98,000 miles, new front brakes and rotors, new front struts and springs, new rear shocks and there's a few other things I read on here to check for and ask about. Even the oil was fresh. No rust on a 2002 Extended Cab 4x4 auto 107,000 miles and I bought it for $8700 straight out. I am pleased but obviously this CEL is a must fix since the annual insepection is a requirement in NY. For now I'm on a 30 day temp plate from Vermont to buy time. Seller has been made aware of the issue and is willing to work with me but obviously I am not comfortable putting nearly $1000 into a new and posaibly unnecessary converter.

The vehicle was obtained by the dealer and driven (based on CarFax) maybe 15 miles while they had it. They do all their servicing at one shop nearby. Saw the receipts and have a gut feeling everything was legit. My thought is that they got the vehicle, the shop saw the P0420 code and replaced the converter. Dealer got the truck back. I came one day later, bought it and drove it home and the CEL came on. Who's to say the converter wasn't at fault all along?

I don't want to chase my tail and again, my wealth is finite, especially after just buying it.

*edit* Thanks JasonLee, I have read it (a few times). It's quite comprehensive but left me with more questions than answers as to how to attack this so that's why I posted.

 

FWIW, I too had a Corolla keep a 420 burning because of an exhaust leak. (never fixed broken stud in head, had to pull engine to get to it)And have seen one from a intake leak. Both of those were easy to find.

It's been said cats can be checked with an infrared thermometer on exhaust pipe before and after. Should be hotter coming out (like 400°) vs. input temps around 300 or less.

 

Had the same code, chased all these same "possibilities". Finally just changed both O2 sensors and haven't had a CEL since. If MAF has been cleaned and light persists I personally would go to the O2's and change those. If problem persists still then start "exploring" these other possibilities. A 150-200 bucks is cheap when compared to the headache of chasing potential ghosts all over the truck.

Edit: Just checked Rockauto and if your're truck has the 3.4 V6 both O2 sensors only run a 160 bucks for Denso OEM's.

 

Sandman is right to rule out whatever you can test before committing to changing anything. $200 wouldn't have been cheap if the light came back on.

 

UPDATE: Decided to work smarter not harder. I own a small body shop. Local Toyota dealer is one of my customers.

Dropped it off for diagnostic. They just called, they are saying it's the FRONT pipe and cat that need replacement..... $1400+ I think I'm going to be sick.

I called the dealer I bought the truck from (mind you, different state, 5 hours away). He said he'd call his guy and see what he can do. Don't know if I'll hear back, if he'll simply refer me to him for a discount or what.

All I know is I can't possibly swing $1400 for a cat. No way. Guessing that nifty O2 simulator isn't going to help in this case either.

 

Yea dealer prices suck. Check the easy stuff we told you to check.. Then do the Sim if you want to cover it up, or replace the cat...

A dealership doesn't fix things.. They replace parts/assemblies.