Hey what’s up guys I have a 2012 ACURA TL
Code P0420 (Catalyst System Efficiency Below Threshold Bank 1) pop up. I change the 02 sensors . Code is still there . Was thinking if anybody been threw this and wondering what would be the next time? I was told could be catalytic Converter .. if anything can help and point me to right direction that would be great !🙏🏼

Also I just got a wheel alignment and when I drove it again after it was still sorta the same . Still pushing towards my right . Put it back on the lift and re align it because it was off again.. my guy re align it and we went for a test drive and was still doing the same thing . Was told that could be maybe my shocks that supposedly it’s leaking . And I was told it could be my rack and pinion . If anybody experience this please let me know 🙏🏼 Thank you guys

 

I doubt this helps you now that it's been nearly three months later, however it may potentially help future members out. I also had the P0420 code come up on one of my cars. Here's what I did that remedied my situation:

1) For the first implementation, I used this Seafoam product in my fuel tank, for the first full fuel up:



2) For the second implementation, I used this Cataclean product in my fuel tank, during the second full fuel up:



3) For the third implementation, I used this Seafoam product in my fuel tank, for the third full fuel up:



My car has nearly 220,000 miles, and I assume it wasn't kept up to par as it should've been, based on other overlooked maintenance items that I found. I also can't know for certain if the previous owner used fuel lower than 93 octane. These are the steps I decided to take before attempting to replace any parts. So in turn, I did NOT replace any O2 sensors, or the catalytic converter.

I'd advise any future members who come across this issue to try out the cleaners first, not only because it's a much cheaper first protocol, but because it's also simpler.

 

I went through this exact problem, my car would always pull to the right. I have an '09 SH. Once i got new tires it stopped pulling. I got the Michelin Pilot Sport A/S 3+ (they're on the 4 now). After getting new tires it stopped pulling completely. i've had these tires on for a good 60k miles and always corner pretty aggressively. They're fantastic and have worn very evenly. Still no pulling.

 

which o2 sensors did you replace? upstream or down?
Also, the emissions related stuff is pretty fickle...sometimes you have to fix shit and then run it through a bunch of driving cycles for them to clear the CEL long term.

 

P0420 means the rear (after-cat) O2 sensors are doing their job.

Your cats are failing and the O2 sensors are detecting it.

Hopefully you went with Denso/NTK OEM replacements. You can get them from rockauto or another reputable source. If not...put you old ones back in.

Something is almost for sure wrong with your catalyst(s). P0420 is a catalyst low performance code.

 

So, gut them and run defoulers is what I'm sensing you are suggesting

 

I mean...the solution is right there

 

The only reason I have not done so on my 96 Yukon is because I don't know if I can make some money by skrait pipin it and selling them cats to a scrapper