Engine code with ZZP downpipe

I put the ZZP 3" DP in last week.

I got a P0420 code about 2 days later.

i got the 304 stainless with high flow cat.

im guessing the code is from the high flow cat, but i thought i would be able to run it without a code

any thoughts/suggestions

Did you re-use your old sensor? If so you probably damaged it. Very common.

Yeah, it should run just fine with that high flow cat. Mine ran just fine.

But I've heard of cases where people damage that rear O2 sensor during install.

yea time for a new one its like 10 bucs

10 bucks for an o2 senor, were do you get them. WHen I put a new one in mine it was $56.00 which was a Denso.

I was very careful with my sensor and I set the same 420 code with my hi-flow cat. After researching the issue, multiple sources told me it was because of the hi-flow cat. The computer's sensitivity for that is pretty high. I had the car emissions checked (long story for why they sniffed the exhuast instead of OBD2-ing it), and my car passed with flying colors, even with the 3" downpipe and hi-flow cat.
$10 says your new O2 sensor will give you the same code over time

just get the 02 simulator.

maaan, i wish i would've gotten the offroad pipe, im gonna have to get a simulator anyway! lol
zuulmusic, did you just end up with a simulator then?

No I disabled the code with the power tuner.

I've been driving with my 3"dp and high flow cat for a year now. Never thrown a code.

from the ZZP website:

"The 304 works so well, that we can place the rear O2 bung in the 3” section of the downpipe on our 304 pipes. Trying that on our aluminized or competitor’s 409 pipes has produced check engine lights triggering “Catalyst system low efficiency”. By placing the O2 in the 3” instead of the 2.5” section of the pipe, we increase the HP gains."


i have the 304, maybe thats my problem and what they claim is wrong and throwing a code? or do you guys that are problem free have the 304?

maybe my hi-flow cat is actually super mega hi flow.

Interesting. I've got a JimmyC downpipe and high flow cat. I thought they were all the same. Maybe not.

Again if you do'nt have a powertuner a simple $2 100k resistor will eliminate the rear 02 code.Chico.

Chico, I might need to go this route to get my headers to work (if I eliminate the cat).

Can you be more specific about what resister to get, and how does it plug into the O2 harness?

There's a good write up on OQCGP's site Ive been running this system for a couple of years without a problem.Chico.