CBFA O2 Spacer


New member
Ok I have done a lot of research and looked at past forums, and figured I might ask the question once again because most of the helpful ones are a decade old. With cobb's new green speed update new tunes no longer turn off the check engine light for P0420. Well I got a new tune and my check engine light is on. I would have gone apr but they discontinued it, and my only other options are uni/IE. UM is not near me nor are any other tunes that I am aware of. The only reason I haven't gone with uni/IE is because I like having the accessport to swap tunes and look at numbers. Uni doesn't have a pop tune and IE's pop tune is extremely annoying, I like the way my stratified pop tune is now.
So basically I would really prefer to keep the accessport but if it is too hard to turn off the CEL I might as well go a different route. Anyways from what I've read it is really hard to trick the CBFA because of the second O2 sensor. I am thinking if I want to try I can get two adjustable O2 spacers and play with it until it works. Slightly space the first one and the space the second one even more? One issue is finding O2 spacers. They're everywhere, but they're a lot more expensive than I thought they would be. And not a lot are adjustable/cheap, really hoping to not spend $100 on spacers.
Also I don't have emissions where I am, is there a way to just keep it in a constant state of not ready? I'm still confused on how this works but if possible that would be a nice solution. Just trying to keep the light off, don't care about being able to pass emissions.

Anyways that's the situation, let me know what you think the best route to take is and if you know how to get that light to stay off without electrical tape or pulling the physical light out of the dash lmk. Also if you know of any O2 spacers please send the link.


New member
there’s posts describing exactly what you say. 2 adjustable spacers using different size openings.

Can find them even cheaper from China.
Yeah that's what I've gathered. Unfortunately I tried using some spacers from china and my o2 sensor didn't fit, as it didn't go deep enough. I need 90 degree or 45 degree spacers because my o2 sensors barely fit in the tunnel as is, unless I could lay them level but even then I don't think that would work. Just going to keep looking for spacers that work.


Passed Driver's Ed
Found a rip off J style spacer online for about 35$ from Jcarparts. OBD2 Vehicle M18X1.5 J Style O2 Oxygen Sensor Angled Extender Spacer Kit Generic × 1. I put it on with middle insert post cat . Haven't had a P0420 code since. Aftermarket Catted DP on CBFA. Custom Cobb tuned W KO4.


New member
Figured I would follow up here with what I did for anyone coming across this in the future. I tried out one J style spacer on the last O2 sensor with both medium and small inserts and they both worked well except for scenarios where I was cruising with the car at 1500-2500 rpm for extended periods of time. I finally got a second spacer and put it on the middle O2 sensor with the large insert. I've since driven the road and speeds that it used to set off a CEL and it now does not. Will update if this fails but so far so good.


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