hello, i have had a few issues with passing nys inspection.

1)car is trifecta tuned with all parts in my sig, and when i went to get inspected it stated that non of my "monitors" were ready

2)with that said, i flashed the ecu back to stock and did 2 drive cycles

3)i then got a CEL for o2 heated sensor so i just replaced it yesterday into the o2 bung instead of the defouler and car ran great!!!

4)did a drive cycle this am, and got the dreaded p0420 code for cat low

5)so i cleared the code and put the o2 sensor back into the defouler and attempted another cycle but the code came back on.

question: if i put the stock downpipe on will i keep getting this code? or should i try the spark plug defoulers???? i already have the vibrant defouler and it isnt working.

PLEASE HELP looking to get it inspected this week!!!

 

The MPX catted DP sucks compared to the Hahn catted DP. I have the MPX, so I know. The tune should have eliminated P0420, and P013E. I've told people before, either get catless, or get a Hahn catted. All the other catted pipes will throw codes. Either too little or too much air getting to the rear O2 sensor. Hahn got it right.

 

First off, if you put the stock dp back on the code will go away. Second your non-foulers are not working to space it out of the exhaust stream? I run the non foulers in my car and it passes everytime. I'm also HPtuned and not trifeca.....maybe you should try that route.....

 

If you put the stock downpipe back in it should get rid of the code as long as the rear o2 isn't bad.


He said the code came on when he flashed back to the stock tune. I agree with you about the down pipes though, either go cat-less or Hahn catted.