California and Catalytic Converters

[LTSpenny]

Vehicle is a 2016 Chevy Tahoe 120k miles. Located in CA.

Recently completed services:
Oil and filter
Transmission oil and filter
Spark plugs and wires
Decarb service for intake.
New air filter and MAF
Cataclean in system.
Has CIL for P0430
Verified no exhaust leaks, vacuum leaks.

Anyone savvy with California Air Resource Board and what Catalytic converters are allowed on vehicles? It seems over complicated. Is my only resource to go to a muffler shop or can i buy the same part number from GM and replace it and be fine? Have P0420 code and i want to say its my downstream 02 as it seems to be acting like the upstream sensor but i do not know enough about them to make that determination. Ive attached a link to my reving engine to 2500rpms until the 22 s mark. Idling and then pumping brakes starting at 40’s mark. Sorry in advance foe the janky video.

Thank you for any assistance.

 

[Fless]

The numbers would be much easier to evaluate if they were graphed at the same time.

 

[LTSpenny]

The numbers would be much easier to evaluate if they were graphed at the same time.

Yeah im working on getting a better scanner, thats as much as i can get with my current one. So far it is looking like its probably fouled. Going to check it with a temp gun later today to compare them.

Update: found no leaks by blowing air through exhaust (low psi 10) also temp checked inlet and outlet on BOTH at idle im about 350 out of manifold and 250-300 out of each of the cats. However. Im only getting the P0430 code. So next i guess is take off the upstream O2 sensor on Bank 2 and try to boroscope/spray carb cleaner in there see if itll help and start saving some cash for a CA exhaust.

Im also reading that if i have a cat restriction, this may also be causing my idle rpm problem?

 

[Fless]

First post says P0420, last one says P0430. (?)

Since there's apparently a code for only one side (verify that), you could swap the downstream O2 sensors side to side to see if the code follows the sensor.

 

[LTSpenny]

First post says P0420, last one says P0430. (?)

Since there's apparently a code for only one side (verify that), you could swap the downstream O2 sensors side to side to see if the code follows the sensor.

Sorry as I’ve gotten older i miss read words and numbers. It is 100% P0430.

 

[Rygrego]

First thing I would do at that mileage is replace the downstream O2s with OEM new and erase the code and see what happens after a couple of hundred miles. Purchasing CARB approved Cats will cost a staggering amount of money compared to Fed Cats. In California and any other states stupid enough to follow C.A.R.B rules the Catalytic convertors must be CARB certified to be able to pass smog, thus making them as much as triple the cost or more. The difference between P0430 and P0420 is left and right.

 

[swathdiver]

Magnaflow has replacement cats and y-pipes that are CARB approved.

A cat code is a cat code unless there's a massive leak. If it comes back after you clear it and there are no exhaust leaks, it's time for a new cat.

Cheap Chicom cats don't last a year.

 

[LTSpenny]

ok so i got more confusing readings. Earlier just about 15 min after starting the car, i took the exhaust temp readings before and after converter and they were lower after. Drove the car home. Took about an hour. When i got home i took temps again and i was 50-80 hotter out than in. Im going to swap the o2 sensors next and try to scope the cat next.

 

[Fless]

The cats don't work very good at idle, which is why they have integrated heaters. Your most accurate readings are after driving it for a while, after they get some work.

 

[West 1]

Your after Cat O2 sensors should read a very constant line, usually around .700-.800 when the cat is working proper. It does not vary much, if you can graph it with your scan tool you will see a straight line. This shows the cat is cleaning your exhaust. Both cats should read almost identical after cat readings.

IF the after cat O2 sensor is bouncing from .150 to 800 constantly like the front O2 sensor readings the cat is not functioning. Sometimes a failing cat will work better on long trips where there is more flow while working less well at idle in low flow situations.

If you have not yet priced Cats in California grab your shorts. The $200 cat available in 49 states is not available to California drivers. A new Cat might be $1500 and is CALIFORNIA approved. Main reason the Cats are being stolen all over CA. There is a thriving business today that builds protective shields around Cats so they are much harder to steal. Who would have thought?

 

[ReaperHWK]

I read the new epa guidance under Trump is that new cars in 2027+ will not require cats.

It may apply to older vehicles as well.

 

[West 1]

Having visited Los Angeles, or Southern California hundreds of times over the last 40 years, my wife, one of 8 daughters was raised there and has many family still there so we have to make the trip often. I also worked down there for 1 week per month for 8 years. I have seen the air quality improve from brown dirt that burned your eyes every day in 1980 to almost clean every day this improvement in air quality is 100% due to improved Car exhaust since 1980. The population has increased in huge amounts. The cleaner air is due to Catalytic converters scrubbing the exhaust. Today the Cats have almost zero affect on your horsepower or MPG since they are now high flow while still very effective.

I own a 1966 Corvette, factory 327 with 350 HP, you fire up that old No Smog or Cat engine and you will stink from just being around it while running. I have thought about adding cats just to clean up the exhaust for me. The difference in air quality behind a car with good Cats vs no Cats is huge. Since bad MPG and low HP is no longer an issue I see no reason to eliminate CATS at least in the large populations in our country.
Some of the improvements is due to Fuel Injection and electronic timing for sure but Cats clean the exhaust really well.
My son has worked on some Audi and Porsche engines that still pass smog through the factory Cats and are making over 800 HP. Cats are not the problem they were in 1976 when they first came out.

If you are in the middle of Idaho who cares, there is not enough emissions in the few vehicles out there to make a difference. But having seen the difference in LA I do not want to see a change back to no cats.

No Joke, from my Mother In Laws house it is maybe 45 minute drive to the top of a nearly 10,000 foot mountain, Mt Baldy, for 10 years my wife kept telling me that she used to go snow skiing 45 minutes away and that whole time I felt she was out to lunch. One visit we happened to be there right after a rain. The Mother In Laws home was right at the foot of that huge mountain and in 10 years of visits I had never seen it, not even a peek due to all that smog. Today you can see it pretty clean nearly every day even though the population has probably doubled in the past 40 years. Your eyes no longer burn just from being outside. A vast improvement in quality of life.

I still never want to live down there. Way too crowded for my taste.

 

[SpareParts]

I would imagine most of the reason it's cleaner now is EFI over cat's.
Almost no worn out mis adjusted carbs on worn out 100k mile vehicles is probably a bigger reason over cats.

 

[tom3]

Seems to me the exhaust temps should tell the tale? If the cat is doing its job you should see some serious temp differential in and out?

 

[DoubleDingo]

I would imagine most of the reason it's cleaner now is EFI over cat's.
Almost no worn out mis adjusted carbs on worn out 100k mile vehicles is probably a bigger reason over cats.

I respectfully disagree. Have encountered too many newer vehicles without cats and they stink to high heaven just like old vehicles do. Even my Jeep's cat, when it failed due to bad o2 sensor, it was as bad as any older vehicle. Cats do work, and do work well.

 

[Fless]

In Colorado we're stuck with only CARB cats for replacement. Not a Federal cat to be found statewide unless you're in the Black Market.

 

[DoubleDingo]

In Colorado we're stuck with only CARB cats for replacement. Not a Federal cat to be found statewide unless you're in the Black Market.

Sucks, too. The cat for my Jeep was just under 600 on rock auto, 1100 locally!

Fun fact, my 81 C20 is a CA truck, but was manufactured in January, so it was an early experiment by GM and didn't come with a cat or egr valve. Just the air pump, and other items. If I want to add a cat to clean up the exhaust it will be an instant fail when tested for emissions because it was not a factory installed item or an option for that particular truck. I am tempted to add one in with flanges and also have a glasspack made up to bolt in its place just for emissions testing.