SirSpen Posted September 27, 2020 Share Posted September 27, 2020 Hello all - I have a catted invida down pipe and catless invidia up pipe (among a few other mods). Haven't tuned it yet, i want to get it passed emission first. Obviously i'm getting a P0420 (P0420 Catalyst System Efficiency Below Threshold) so my current plan is to just switch to my stock DP for emissions purposes. Question - Will having a catless up pipe by itself cause P0420? I know all states are different but from an initial search, it seems like most people are okay with just catless up pipe. Also if anyone has recommendations for alternatives for the DP swap that i'm not aware of, feel free I don't want to go the non-fouler rout for the DP - my state (UT) does visual inspections as well and i think it would be pretty obvious if the inspector has a brain. Link to comment Share on other sites More sharing options...
Max Capacity Posted September 27, 2020 Share Posted September 27, 2020 After you (or Tuner) delete the code from your system, you need to drive the car at least 60 miles or else the system will show a error when they plug in there emissions tester. Here in CT we have a visual too. my car passes the visual with a catless up pipe and catted Dp. I used to change the OEM Dp back on the car until I replaced the catless DP with a Catted one. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
SirSpen Posted September 28, 2020 Author Share Posted September 28, 2020 I actually already went in to get tested just for kicks (before my initial post) to see if i'd pass after i reset the code using my OBDII but like you said, i must not have driven it 60 miles yet as they told me it wasn't ready - But i did pass the visual inspection which is nice. However now that i have driven it and the codes reset, the code is back. But you are saying as long as my tuner deletes/disables the code, it will pass emissions? This would be nice. don't really want to spend more time swapping DPs back and forth.. Link to comment Share on other sites More sharing options...
Max Capacity Posted September 28, 2020 Share Posted September 28, 2020 P0420 Catalyst System Efficiency Below Threshold (Bank 1) You need to replace your front O2 Sensor. Denzo 234-9120 I'm amazed at how the prices very from time to time of the year. https://www.google.com/search?q=Denso+234-9120&rlz=1C1OKWM_enUS906US906&sxsrf=ALeKk02OTt6VdUvRo8MJgWABI3T-MuXfxw:1601313473971&source=lnms&tbm=shop&sa=X&ved=2ahUKEwirz6jGrYzsAhURknIEHZqvAQQQ_AUoAXoECBkQAw&biw=1280&bih=881 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Max Capacity Posted September 28, 2020 Share Posted September 28, 2020 https://www.amazon.com/gp/product/B001F799X6/ That's from a few years ago. Post # 172, https://legacygt.com/forums/showthread.php/idea-web-links-saved-various-parts-219238p5.html 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Max Capacity Posted September 28, 2020 Share Posted September 28, 2020 The catless up pipe will not cause that issue. I mis-spoke, the Tuner can delete the rear O2 sensor code. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
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