P0420 question

As long as the sensors are good, that means the cat has lower Oxygen Storage Capacity than a working Prius cat is supposed to have.

And generally, if the sensors aren't good, there will be a code for that instead, which will prevent the OSC test from even running.

 

Some computer person needs to work on some type of a firmware update that can make that OSC test go away or just be decided that it never needs to run and that will solve this whole issue with the catalytic converter business pretty much forever other than the sensors going bad which aren't like you said a different code I see no need for the car to be testing its own catalytic converter with some type of flood test or whatever it is and if this is so necessary why isn't it done on cars which much nicer engines if you will More expensive all of that I would think this is a feature you'd want to stuff on your most expensive car that you sell and make so that people would be running back and forth to buy parts from them for them. Not on your bread and butter family hauler that needs to be online and working not sitting in a parking lot testing itself for its catalytic converter functionality holy Christ. So other than revenue building the OSC test has no valid reason to be programmed into the computer system No?

 

I suppose they do the test because the catalytic converter is there to do some actual chemical stuff, not just for decoration, so they'd like to be sure it is doing that. There might even be a requirement.

 

But I don't think all of our other Toyota's do that like an '09 Corolla or whatever I have here. I don't think an 11 2z Rolla has it. But I'm not certain but I know it doesn't have this 0420 code issue Not in the 300K that it ran at our place so I don't know I don't know who's requiring what but other catalyst her systems in lots of other makes of cars and whatnot I guess Don't seem to have this problem or they don't do this or whatever the heck.

 

P0420 is a code in the P0 range that is SAE standard across car makes and models. So I would guess a lot of cars check that.



On the other hand, a Prius is very demanding of its catalytic converter. It doesn't just warm up once and stay lit off for the whole drive. So a Prius is equipped with very high-spec converters (witness their popularity with cat thieves).

Probably, when you put in an aftermarket Corolla converter, you are not putting something in that's as far below original spec as you are when putting in an aftermarket Prius converter.

 

This isn't about revenue building, but rather catching high and gross polluters. It sounds like you don't care too much about high emissions, which is fine I guess, but many of us do and many states care enough to deny registration if your vehicle falls into that category.

The test itself is very straightforward and is particularly good at determining the ability of the catalyst to store enough O2 to convert Oxides of Nitrogen (NOx), caused by the combustion process, into CO2 and NO. While the test can also measure the effectiveness of oxidizing CO and HC, there are easier ways to test for that, but NOx is a lot harder and this easy test is very effective at that.

As an aside, this is also a useful foil to those wanting to use a spacer with the rear O2 sensor to add a bit of delay to maybe make the cat seem to be compliant. This can work if the cat is not degraded too much (a borderline P0420) but won't really work if significant degradation has occurred. The DT (Delta Time) between system commanding rich and commanding lean of a healthy Prius cat should be 2sec or greater when looking at the DT between the front O2 and the rear O2. That DT is the capacity reading of stored O2. I'm not aware of the actual threshold for failure, but I suspect it would be somewhere between 1 and 2sec. Others may have more information on this, I've just never found the threshold value. If you start at something like 0.245sec DT you will be unlikely to trick the system with a very long spacer since other issues would arise.

 

I actually do very much care I lived in Western Massachusetts in the early '80s late '70s when emissions testing was just coming online in the Northeast or at least when it was worth talking about and so all of my friends that own garages all of a sudden had to get exhaust gas analyzers and this stuff was done by numbers this is before computers and before all the real funny business started You had to have a number 7% blah blah blah whatever it was I knew what those numbers were and it kind of was pretty funny to me that my Corolla in 1973 that didn't have a converter was pretty darn clean then in oh I don't know let's pick 1982 my TE72 wagon which is a hemi-headed Corolla wagon with a converter was dirtier than my 73 SR5 Corolla with the same hemi-head 2. TC engine. I immediately knew there was funny business in the mix just by seeing this then 85 when I had hachi roku's which is AE86 Corollas with the infamous 4AG little twin cam engine I could take my converter off the car got it completely put it back on the car welded in place pull it into the shop put the exhaust gas analyzer up the tailpipe and the car ran just as clean as it did with the converter The numbers say so right on the paper If they didn't I didn't get an inspection sticker that's how I found this out. So no I generally am not trying to pollute the planet I don't drive vehicles that are burning oil and blue smoke is coming out the tailpipe none of that Cheech and Chong crap. But I do believe that the powers that be should stick to trying to use the powers they have to do whatever it is they do and stay away from the likes of my automobile that would be a real good idea and many counties in the land are picking up on that and are dumping things like emissions testing because reality is it doesn't really do any good It creates a lot of criminality in the auto business etc etc like the old teamsters Union in New York you know price fixing price gouging all of it.

 

2nd gen pings on 87 octane at sea level of CEL is lit from P0420 code. 3rd gen won't ping. If u ping, go to 89 octane to resolve it. Aftermarket cats all throw the code. OEM is the only option

 

If the only thing wrong to cause the P0420 is the crappy cat, then no that won't hurt anything except your eyes constantly seeing the MIL

Your member info says you are in Colorado. If that's still the case your state only allows state exempted 3rd party or OEM cats as legal replacements. Yours is most likely illegal. That law went into effect 1/1/2021 under Regulation 20.

Since the MIL will be perpetually lit it would be a very good idea to have a decent scanner program to run regularly to see if there are multiple trouble codes because all you will see is the check engine light on and won't know if any other trouble conditions have popped up. In essence you are crippling your early warning system and will have to go manual with regular checks.

 

I test the exhaust system - ZERO leaks anywhere ahead-near the cat and sensors. Both A/F and O2 sensors working (can read rich and lean conditions). Fuel Trims at 0 +/- 10%. No misfires.

If all that's good, then it needs a cat. (Oil burning will kill a cat - eventually).

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