997_rich

I have GMG headers, 200 cell GMG cats and a GMG center exhaust. I've been running this setup for about 5 years now. No problem passing smog etc. Occasionally I get an O2 sensor fail code on either side of the engine. It happens maybe once every three hundred miles. Usually it's a cold morning or run through some rain etc. I assume the cats aren't fully up to temp or whatever. It's not a big deal but I find it annoying.

I plan to put an 02 sensor extension in to make the o2 sensor less sensitive and I have a few questions:

1. One sensor will interfere with a bracket. Is it better to use a 45 or 90 degree extension for that one?
2. any recommendations on brand etc?
3. there are some that have a mini cat inside them... is that worth considering? https://www.fvd.net/us-en/FVD111LAMS...ividually.html




1.

RAudi Driver

1. If you can make it fit with a 45 then a 45, but both should work fine.

2 & #. I like FVD's stuff and that baby cat is the cutest thing in the world.

Wonderdan

On my Dundon 1.0 even with the extensions it triggered once and a while… I think I had fabspeed spacers, I mounted at 90 and fit them ok w/out having to remove anything. I think the 45 might have actually been better though.

I also replaced all o2 sensors while I was at it

kinetic125

I have stock headers, stock catalysts, and Fabspeed straight pipes on my 7.1 GT3.

Before I installed the FVD straight extensions, I was having frequent O2 sensor codes, but after the installation of the extensions, I have not had any problems (touching wood).

I know this doesn't exactly help answer your question, but it is proof that the basic concept of the extension works as needed.

Enjoy!

997_rich

Thanks for all the responses!

TD_05

May I ask what codes you guys were getting? I am getting occasional O2 sensor codes on my car with an aftermarket exhaust as well.

Thanks,
TD

Wonderdan

it’s usually one of these

Evolved Rs

Stuff steel wool in the extenders. It'll eventually burn off over time but has prevented efficiency faults on my RS and M3.

Wonderdan

There are two types, o2 extenders and then cat extensions for o2 sensors.

One just adds space and in theory more oxygen between the sensor and the manifold. The other actually puts a tiny little cat in between.

Pelican parts has one here

https://www.pelicanparts.com/More_In...yABEgJoifD_BwE

a little less $ than fabspeeds, however these are all Chinese OEM so you can find your own on Alibaba and test them before spending all that $$. Infact the ones I found were an exact replica of Fabspeeds.

https://m.aliexpress.us/item/3256803...ed3f0698f63dcd

https://m.aliexpress.us/item/2255799...f-b16ad7e97abe

limitedslip

I have a pair of Vibrant J-style (90°) spacers I am not using if interested. Like-new condition.

kinetic125

Yes, I too was on the P0430 (and the bank 1 equivalent) bandwagon before installing the O2 sensor extensions.



P0430 Catalyst System Efficiency Below Threshold Bank 2

TD_05

On my car with aftermarket exhaust I am also getting occasional P0430. But in addition, getting P013, P014, P015 delayed, slow O2 sensor rich to lean bank 2 sensor 2. Has occurred 4 times in the ~4 years I've owned the car. Would you guys feel these codes is worth chasing / fixing?

Wonderdan

If you’ve already replaced the O2 sensors, which are good to replace anyway then I’d say no… OEM are twice the cat (400 cell) than the high flows are so if it’s not bugging you then I would ignore. If you have to pass emissions then that’s a dif issue.

TD_05

Thank you.. AS far as I know car is still on original O2 sensors. I'll have to double check records from PO's. No emissions requirements for me though, also happening quite infrequently...

TD

Wonderdan

May want to replace them anyway… it’s not just sensing your emission it’s trying to balance your throttle body and fuel. So if you get some weird activity like hesitations on throttle etc it might be good to replace… very easy DIY