I'm not sure if this is the right forum for this question but here it is, I installed my AEM Uego wide band afr, on the rear bong of my catless helix dp, and for some reason i got a cel, i used to have the little spacer to fix cel when i ran the stock o2 sensor in that dp, but i guess it doesnt fit? so anyway does anyone know how to fix it?

What is your CEL code? P0420?

not sure my friend scanned it and he said that it was because of the wide band o2 sensor being in.. but i didnt see the code my self why is that a common type of code?

If you removed the rear o2 then yes you will get a CEL.

Engine management will get rid of it, or use the tools at openecu.org thats how I removed mine.

but if i remove the CEL with utec, from what my friend told me it would take the cel off completely which means it wouldnt even come up if there was nother code that poped up

^ you are correct. Don't disable the CEL with the UTEC as it disables ALL CEL's. You need something else, like AP or a reflash, or use tools from openecu.

ok 2 things, whats an ap, and i'm very uneducated on engine management let alone mess with it so what exactly am i looking for on epenecu? and who do i do it?

Cobb AccessPort. http://cobbtuning.com/sti/accessport.html

well i have UTEC so how would i do it, and how would i use that website to do it..?

The link I posted is for the "AP" that Gethin suggested. It can disable specific CEL codes, like the rear AFR sensor one.

I believe that the UTEC is an all or nothing proposition when you disable CEL. It sure would be nice to have the option to disable specific CEL codes via UTEC.

You don't want to disable the CEL as you said with the UTEC. Not a good idea.

The Accessport is a complete engine management system, overkill as you already have your UTEC. I did not realise from your first post you had an UTEC.

The simplest / cheapest thing for you to do is to weld another bung in your downpipe to accomodate the wideband o2, and keep your stock o2 where it is. Keeps the stock ECU happy and you also have wideband.

The openecu method involves buying (or making if you so wish) a openport compatible cable (www.tactrix.com) for $80 and using the open source tools (the STi software I think is going to be ready any day) to read your ROM file from your stock subaru ECU and using a HEX editor to hunt down the correct offset locations for the rear o2 CEL's and overwite them with a null code. Here's an example of how I did it on my car, the WRX has been supported for a while (I also disabled the EGT CEL too since I was hacking around in there) http://www.openecu.org/viewtopic.php?t=315 If you are the sort of guy who likes to tweak (I assume you do as u have the UTEC) then go for the openport solution, you can then use the other toys too like Enginuity, TunerPro or ECUEdit, all in development of course.

lol i would love to tweek i just never had, and i'm still learning about this car so i'm pretty paranoid about blowing something up! lol but still this is some good info.. thanks man