just threw a P0420 Catalyst System Low Efficiency ECM, PCM....
i have a magna flow highflow cat with gmpp cat back and a zzp midlength and dp..

any suggestions?

 

im intressted in this as well..im orderin the same setup...how do u like the setup

 

i love the setup very subtle at idle and sounds good at wot but u can still hear ur s/c (sorry megan exhaust owners but ur exhaust is way to loud for the street)

 

I had that problem with a custom header and cat. The cat was to far downstream and it got to cold at idle to light off. Either that or the cat isn't doing its job.

 

odd...not unexpected though.

 

is it one of those just let it go and clear it all the time or should i take it apart and look at my cat for clogging?

 

My buddy bought that same downpipe and the cat took a **** like the stock ones do. Better pull it off and replace it or run a straight pipe man.

 

Stouffer had the same problem, he bought a adapter to the o2 Sensor after the cat and we put it in and cleared the code, light has not been back on yet.

 

turn it off..I can send a fix

its called, turning the code off

 

lol i did bud

 

Don't think turning the code off is gonna work when you try to go through emissions if you have to in some areas like we do, the spacer we put in limits the airflow over the o2 sensor so I'm figuring it compensates for the extra flow you get from the highflow cat. He was gonna drive it some more to make sure the light stays off. I'm don't remember where he got the spacer from did have to do some cutting into the body to make the sensor fit though.

 

everyone has a price

 

so wats the fix to this?

 

turn the code off that simple

 

well thank you captain Odvious, your powers of deduction amaze us all!
Now if you went to the dealer and they "just turned it off", you all would be pissed! This guy is looking for an answer and you give him this crap.
You need to know if the cat is doing its job, put the factory cat back on and see if it throws the code again, if it does, i'd replace the downstream o2 sensor

 

duh....I turned mine off and made it so it won't make the SES light come on.

 

if you have an O2 issue, your not getting max perfomance out of your motor, the O2 sensors adjust fuel trim and catylist damage isnt good, especially if you paid for your cat.

 

The rear O2 sensor doesn't mess with the afr....it does monitor the cat performance, although with a hi-flow cat it isn't properly calibrated. No clue how to change it either.

 

It sure does, it reads what is going on upstream and adjusts accordingly, it also dictates if you are in open or closed loop. if your closed, your just dumping fuel and you can fill the cat with unburnt gas causing a cat efficincy code.

 

ok...

 

hey, im not here to make you look like an *******, i just want to help this guy, im sorry if i called you out, wasnt tryin to do that

 

I don't need any help.
The MAF and MAP play roles in the OL/CL....If the rear O2 sensor does, it isn't a big one and can be turned off rather simply. Having unburnt fuel in the cat is an issue, but not when COT and DFCO are turned off (which they are in his tune).

 

OH, didnt realize he was tuned, sorry, that changes everything, you will have to get back into the ecu and initalize the module to relearn the o2 sensor values. Not sure how on HP tuner but i had to do that on a ram at work with all aftermarket stuff using bullydog software

 

im sure doc will do it when he tunes my car again

 

heh thats going to happen when you buy a high flow cat, just have someone remove it with hp tuner