Riding dirty!!! Is there an easy fix for P0420 code

I'm terrible at getting my tags paid on time. Paid late fees every year for the past 10 years. Late fees are the least of my problems. This year the truck wouldn't pass smog. CALIFORNIA gotta love it! P0420 pshhhhh!!!!!
I tried crc guaranteed to pass: no luck
I tried a gallon of laquer thinner: no luck
Seafoam: no luck
Fuel injection and gas cleaner: no luck
1 bottle of cataclean: no luck
Now P0420 and the P0430 code are thrown
I have been driving with expired tags for 4 months and haven't been yanked yet. Knocking on wood til' my knuckles bleed!!!!
I cannot afford to change the 4 cats on this damn truck. Dealer wants $4k. No aftermarket cats allowed in CA at least for this guy 195,000 miles and the truck runs great. Any suggestions?

 

You only have 2 cats on the 4.0L. Cats are attached to the manifolds, and resonators are attached to the y pipe. I had a 430 code a few weeks ago. Changed o2 sensors, spark plugs, cleaned maf and TB, seafoam in gas, sea foam in intake all with no luck. May have helped though and eventually got me where I'm at now. Then heard about cataclean at AutoZone. $25 dollar bottle of I hope this works. It did for me. Though, it may not give the same results in every instance. Read the instructions and follow them. Pour whole bottle in 1/4 tank of gas or less, drive 15 miles, fill up tank. I did that, in high rev, two fill ups since, and all seems good. Hope that it might work for you as well if you try it.

 

Try the 02 sensors first.

 

Do you have soot around the header to y-pipe flanges? If so, the gaskets are bad and replacing them might fix your issue if the cats aren't bad.

With that age on the rear O2 sensors, you might need to replace them. You can test them, or just replaced them. Up to you. Could even replace one sensor at a time, and see if it clears the associated bank's code. Amazon has them at a good price. Be gentle as they can break easily internally if banged.

When you were smog checked last time, were emissions in range, but the CEL's still on? I don't even know if they would go that far, with the light on?

If so, an O2 simulator, or J-bung adapters, could get you by for a little bit.

 

Got my o2 sensors on rock auto, slightly cheaper than Amazon.

 

Tried cataclean today. Maybe should have bought 2 but I'm up to $100 on fuel addatives and I feel like I'm playing a carney game you'll never win at the state fair. Ordering the O2 spacer from eBay now.

 

Oxygen sensor spacers!!! They really work. One on each rear (downstream) sensor. Can't wait to get the truck smogged. $10 and a little wrench time. O2 sensors are a pain in the ass to remove.

 

Make sure to use copper antiseize on the sensors. Silicone based antiseize will damage the sensors.

 

Did you get this figured out? I have the same code problem, haven't started working on it yet, got a code reader and about to order some O2 sensors

 

Most auto parts stores sell them under a weird name, but they work. I've got a stack of different styles in my garage. Ended up needing some 90° adapters on my Lexus after an exhaust upgrade.

EDIT: Spark plug non-fouler

 

http://www.raimotorsport.com/Threaded-J-Pipe-with-Gas-Flow-Inserts-for-CEL-prev-p/11619vib.htm
Used these on my 2009 2 years ago. Problem solved.

 

My 2005 Tacoma failed with P0420 and P0430 codes during smog check.

I replaced my 2 down stream o2 sensors, reset the codes, drove around and Check engine light came on.
I pour cataclean, seafoam into the gas tank, reset the codes, drove around and check engine light came on.
I changed spark plugs, replaced air filter, reset the codes, drove around and check engine light came on.
I removed upstream o2 sensor, sprayed seafoam in, ran the truck while smoke came out my exhaust for a while, reset the codes, drove around more and the check engine light came on.

Finally, I added non-foulers on the down stream o2 sensors, reset the codes, drove around, no check engine light.

Took the truck to get smogged and it passed...

$5 non-foulers from Amazon on each of the two down stream o2 sensors.
Link here: https://www.amazon.com/gp/product/B0002JMS6I/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
Refer to this youtube video: https://www.youtube.com/watch?v=J1pOJ1Hn-wQ

I've read that you must use OEM o2 sensors with this hack.
Link to o2 sensors:

$47 Denso 234-4260 Oxygen Sensor

https://www.amazon.com/gp/product/B00199FBQY/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

$45 Denso 234-4261 Oxygen Sensor with 4-Wire 10” Harness for Lexus/Toyota V-6 Downstream Left/Front

https://www.amazon.com/gp/product/B0016NBBQW/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

Please note, I believe they can still fail you if they notice the hack on the visual inspection. I guess I was lucky and they must not have done a visual on my re-test.

Good luck.

 

Mine had 0420 and 0430 as well. Exhaust was leaking out of all of the flanges in the y-pipe. Replaced the gaskets at a shop for like $150 and no more codes.

 

Recently had it on a 2010 4-cyl. The first cat was GONE! I’d unbolt the Y-pipes and see if the cats appear intact. You also see which side the code is being thrown on. IF you have to replace a cat you could at least just replace ONE on the faulty side. I haven’t priced an OEM cat, but $4k has to include some high labor costs.

 

Cats are ridiculously expensive because they contain exotic metals like palladium, platinum, rhodium. In general, the OE cats have more content (more $) because they need to last 8 yrs or 80k miles.

The spacers work as far as turning off the light, but they only fool the sensor - you will still probably fail a tailpipe sniffer if one or more cat is not functioning properly.

 

I pulled a P0420 code (my first check engine light in 134,000 miles) about 3 weeks ago and put it off as a dirty O2 sensor as I had no negative driving impacts. About a week ago I had a very noticeable rattle that sounded like it was coming from the dash area that was more obvious with harder acceleration. I took it in and they confirmed that it was my catalytic converter that tripped the code (<30% efficiency) and that the vibration and rattle that i was experiencing was the disintegrated honeycomb of the converter being whipped around in the exhaust. I then had just about the most unnerving 100 mile drive of my life to my hometown mechanic (in CA) with highly reduced power and what sounded like a major exhaust leak. Total with labor came out to a little under $1900 and of course smog is due this month...

 

What did your mechanic say ended up being the issue?? Sounds like someone took you for a ride. Even if you had to replace your cats, that should be way less than 1900 bucks.

Are you still having the p0420? Check out these o2 simulators. Gets rid of the CEL if its a bad cat causing the issue

 

My downstream O2 sensor was completely out of service and I had been pushing my truck pretty hard the past couple of months. I commute ~70 mi a day and have had a few 500-600 mile days up and down 395 mixed in there. The Cat efficiency is what triggered the code but they were unsure if the debris caused the O2 sensor to fail. The Cat itself was ~$1200

 

IIRC AutoZone had 50-state OEM quality cats already installed in the pipe between the collector and the muffler for under $700. Just four rusty bolts and two gaskets is all it would take to swap.

 

02 simulator isnt going to help with the flow of exhaust out of the engine.
The catalyst material was broken into chunks and blocking the exit of the exhaust pipe. Its rare but it does happen and it will absolutely cause a lack of power.