P0430 code

[bigdrtrdr]

I know this is a common code and Ive read through the related posts,
So my 02 Tahoe 5.3 189k threw the 0430 code.
The vehicle runs great, no smells or smoke, smooth idle, starts great, plenty of power
I replaced the downstream 02 sensor bank 2, cleared the code and it was fine for a couple days and then the code returned.
Vehicle still runs great but i am confused.
any help would be appreciated
Eric

 

[swathdiver]

I know this is a common code and Ive read through the related posts,
So my 02 Tahoe 5.3 189k threw the 0430 code.
The vehicle runs great, no smells or smoke, smooth idle, starts great, plenty of power
I replaced the downstream 02 sensor bank 2, cleared the code and it was fine for a couple days and then the code returned.
Vehicle still runs great but i am confused.
any help would be appreciated
Eric

P0430 is not for a sensor, it's because the cat is dead or you have a massive exhaust leak on that side. Nothing else. Aftermarket sensors don't play well with the computer system. Bad sensors have their own codes.

 

[bigdrtrdr]

P0430 is not for a sensor, it's because the cat is dead or you have a massive exhaust leak on that side. Nothing else. Aftermarket sensors don't play well with the computer system. Bad sensors have their own codes.

Thanks for the information,
Is it possible for the cat to die and still flow?
No exhaust leaks at all

 

[drdave81]

Yes, it monitors the efficiency of the converter. Basically, your upstream O2 measures the exhaust coming from the engine, then the downstream measures your exhaust after coming out of the converter, and the PCM compares the two readings. If the PCM doesn't see enough of a difference between the two sensor readings, it will determine that the converter is no longer doing its job properly.
So your converter doesn't have to "die" in order to be bad. It's just no longer efficient enough, as far as the PCM is concerned.

 

[bigdrtrdr]

Yes, it monitors the efficiency of the converter. Basically, your upstream O2 measures the exhaust coming from the engine, then the downstream measures your exhaust after coming out of the converter, and the PCM compares the two readings. If the PCM doesn't see enough of a difference between the two sensor readings, it will determine that the converter is no longer doing its job properly.
So your converter doesn't have to "die" in order to be bad. It's just no longer efficient enough, as far as the PCM is concerned.

Thank you, very helpful
WA state no longer requires emission tests and I am considering not fixing it and just check occasionally for other codes.
Thoughts ?

 

[swathdiver]

Thank you, very helpful
WA state no longer requires emission tests and I am considering not fixing it and just check occasionally for other codes.
Thoughts ?

That cat will likely continue to degrade, fuel mileage will go down and as it breaks apart you may hear a rattling noise at idle. Worst case is that it will cause lugging or stalling. I considered hollowing mine out or putting in an off-road Y-pipe but remembered that I didn't like the stinky smell of an engine without cats, especially since my wife and kids use the car.

 

[drdave81]

Guess I should have added that. Yeah, it will eventually "die". Die, meaning just what swathdiver said.
You either have to replace it, or deal with the excessive noise and smell, and check engine light on if you don't get it tuned out. Some people have found ways around the downstream O2s other ways, but it seems hit or miss from what I've seen.

 

[OR VietVet]

To ignore the problem does not fix anything. That cat will eventually clog up as it breaks down and that will create a whole other list of problems, especially with the power of the engine, caused by excessive back pressure from the clogged catalytic converter. IMO, spend the money, replace both catalytic converters and all sensors with quality sensors. As @swathdiver said, crappy new sensors create their own set of problems.

By the way, welcome to the forum from Oregon.

 

[bigdrtrdr]

Thanks for all the info,
Ill get it fixed soon

 

[rockola1971]

Clogged cat will burn an exhaust valve and/or melt the head if ran like that too long.

 

[Fless]

WatchWesWork on YouTube just posted an interesting diagnosis of a clogged cat. He has a decent explanation of his reasoning near the end:

 

[OR VietVet]

I love the red dice for valve stem caps.

I like the explanations for his train of thought and how he reaches his conclusions. How many times have you or I heard that when a parts store reads codes for free and they get a P0101 MAF sensor circuit code.......it means you need a MAF sensor and the parts store happens to sell those. But, I have had customer's want my W-A-G and go with that.