Got the new 3 in, weld-on DP and cat from zzp.

Had to get new downstream 02 sensor as well.

Now Im getting CEL. Code is P0422 Main Catalyst Efficiency Below Threshold.

Ran car a few days without rear o2 sensor,caped bung for a few days till got new sensor installed.

Had 2 codes pop up, one for the lack of 02 sensor, and also the P0422 mentioned above. Then had them both cleared.

CEL came back 1 day later. This time only one code, P0422.

Whats the deal with this!? Id like to enjoy new mod! I was already set back an additional $80 for a new o2 sensor cause old one was seized up in the stock pipe. That already put enuff of a damper on things.

Does it have to do with the cat being "high flow"?

Any and all advice/thoughts are greatly appreciated.

 

I believe that's caused by the Hi flo cat.
It's going to keep coming up unless you switch to oem cat.
of course you don't want to haha, you need a new tune/ zzp stage 1 pcm it removes the cel light for that issue.

I think Amy, AwesomeSS went through the same issue.

Good luck.

 

x2, these cars don't like non-OEM cats. Well, I should say the PCM doesn't. My dad has an '02 LS 3.4 with an all stock exhaust, except for an aftermarket cat and it always throws a code for it. It doesn't have any driveability issues and gives a consistent 25-26 mpg, so I think its fine.

 

You bought an aftermarket cat, on the website it explains that you will get a CEL because of the higher flowing cat.

Only fix is to tune out the code or remove the downpipe.

 

You need to get your PCM reprogramed and get that code tuned out.

 

okay so easy fix the engine light will always come on now because the high flow cat doesn't do as good a job as the factory PCM tuning would like to see. there is a product called a O2 emulator it mimicks a good O2 signal so the CEL stays off. go on 3800performance.com its $59.99

 

I saw this on their website and was wondering if this would take care of it.

 

You can't use the o2 emulator on a 2005 because it reads multiple factors unlike the 2000-2004 cars.

 

Too bad for the original poster. I'll ask my dad if he wants to spend the $60 + shipping on his 2002.

 

Might as well spend the $100 on a tuned PCM with the code delete and extra fun.