i used one of those code scanners and erased it it will come back and if you do emissions testing in your state it will appear still on there scanner or say that certain code needs to be reset.

if you want it permanently gone forever and it be emissions legal it needs to tuned out. i had mine dyno tuned and it never came back and passed emissions test.

 

I had zzp delete it from my pcm. if your gonna spend 50 bucks on an o2 emulator, might as well scrape up 50 more bucks and get a canned pcm from zzp, select 0420 code delete from the drop down menu.....wont have another problem. Thats what i did, i've had no problems with my high flo cat. might as well spend the 50 bucks more and get the perks of the pcm and no issues.

 

The pcm seems to be the logical choice, but I was thinking of waiting till all the mods are done before getting a pcm or a dyno tune... while using the non-fouler mod as a stop-gap measure since it worked for other set-ups.

 

It took my car over a month to trip the CEL for the P0420 code. It was my understanding that the o2 sims wouldn't work on only the 2005 because they changed to a different way of reading the o2 sensor.

Either way I would vote for just tuning it out of the car instead of an o2 sensor fake. It's what I'm going to do when I get a few of my mods in first.

 

That sucks Mike that you threw a code. I'm on 2 weeks and no code. I did replace the O2 sensor if that makes any difference.

 

So did I... My last one was fried into my stock downpipe and I wasn't allowed to walk away from the mechanic's without one :P

 

ya same here - I hope I don't throw a code - I don't have access to a HP tuner. I guess my other option is to get the PCM from ZZP for 100 bucks.

 

i've been reading this thread for a while and similar threads so i thought i would chime in. i'm not as familiar with the downpipes on these 6th gens as some of you are since they are not available for my car, so i have a question:

what exactly causes the code? it's not the actual downpipe is it? from my understanding it only comes if you have a high flow cat or bad O2 sensor, right? couldn't a person just install the downpipe with a stock cat and have no problems? do the high flow cats really help that much that you have to go to much more trouble just to get rid of the code? thanks for the info guys.

 

You needn't worry about it, your car is fine. It's for us 00-05 guys.

 

Well, the stock downpipe is extremely restrictive and the aftermarket one opens it up and with the high flow cat makes it breath better. And that mod is a must if anyone is planning on putting a smaller pulley (for supercharged models) on. But when you get to the advanced mods the car should be tuned properly.