Code P0420--but no cat!

[patsfan4life]

So when my car turned 100k almost the same time the CEL came on (go figure) anyway, i had it scanned and it said P0420, and from my understanding that means time to get a new cat. The only problem is i dont have a cat, so what else could this be? Searching online the Cat is the only thing I could find that triggers that code.

 

[EM0jerK]

do you have an spark plug Non-fouler on the second o2 sensor?
if not, put one and reset your ecu.

 

[WillDeStijl]

confused

btw, I have this same error code.

I'm confused (Please excuse my ignorance)... I think all late models come with a cat. I would think that if you no longer have one, then you'd DEFINITELY get that code (because the 2nd O2 sensor would detect that the cat is not working "above threshold" SINCE IT'S NOT THERE TO DO ITS WORK!).... am I nuts?

AND... I'll take your word for it, patsfan, that the SPARK PLUG non-fouler will fit the 2nd O2 sensor, but what good will that do anyway?

Is it stupid to try to clean out my cat somehow? I cleaned my EGR valve to correct another code, and that went swimmingly.

 

[bazooka joe]

maybe i'm missing something here..(dunno)...if you don't have a cat then you need to "trick" the ecu into thinking it's still there...if you don't you'll bet that code from the o2 sensor....make sense?

 

[terbow]

the non fouler trick will prevent the 2nd o2 sensor from throwing a code. It thinks theres a cat thre due to the restricted flow the non foulers provide.

btw, I have this same error code.

I'm confused (Please excuse my ignorance)... I think all late models come with a cat. I would think that if you no longer have one, then you'd DEFINITELY get that code (because the 2nd O2 sensor would detect that the cat is working "above threshold" SINCE IT'S NOT THERE TO DO ITS WORK?).... am I nuts?

AND... I'll take your word for it, patsfan, that the SPARK PLUG non-fouler will fit the 2nd O2 sensor, but what good will that do anyway?

Is it stupid to try to clean out my cat somehow? I cleaned my EGR valve to correct another code, and that went swimmingly.

 

[TheMAN]

cat don't work = cat not there
DUH

 

[WillDeStijl]

I bought the non-fouler, and I see what its purpose is now: to move it back out of the path of the exhaust, and only allow a little of the exhaust through the small hole to where the sensor is barely able to 'do its work'.

It seems a bit shady, but I'm on board. We'll see how it goes.

 

[terbow]

well the other alternative is wiring in an 02 modifier that tricks the ecu but id rather not hack up a 70$ sensor to do that. plus this is proven time and time again. you have to buy 2 non foulers, drill the first one to 1/2" so the sensor can be installed, then u put the non drilled one on after that, then screw it into the pipe. you cant jusr use 1 nonfouler it wont work.

 

[patsfan4life]

Wow, this thread came alive, that cat code I got when i started this, happned right at 100,000miles. I went had it erased and it never came back. Mazda porbably programmed taht so i'd go spend to get the cat replaced at 100k but nope not me cause cat free is the way to be!

 

[dbMazda]

Is all cats gone. You can't leave one, the one cat will have to do the work of 2 & will burnout faster. It's all or nothing. The ECU doesin't know the cats are gone, so it reads things as being too rich. So it turns down the fuel. So you need to turn up the octane.
Less of 91 octane = about 87 octane in combustion.
You could "cut back your spark plugs." More fuel burned is less read by the O2 sensor.
http://performanceunlimited.com/documents/plugsidegapping.html

 

[tweety2300]

Most ignorant post and old thread bump nominee right there^

 

[Installshield 2]

Most ignorant post and old thread bump nominee right there^

couldn't agree more...