o2 sensor question

[yergi]

Firstly, I did do a quick search, so appologies in advance if this question has already been answered;
For the o2 efficiency sensor in the midpipe, will it throw a CEL with just one cat prior to the sensor? Just the cat in the downpipe will be there. All others will be gone... I am getting restless waiting on my accessport, but didn't want to do anything to put it in limp mode before I have the ability to clear the errors....

Thanks alot.

[fc735]

you dont need to worry about it effecting the way it runs....the downstream O2 is there for monitoring the cat only....

but, i would wait to see if it sets it, sometimes it will, sometimes it wont with just one cat (you didnt mention if it was an aftermarket DP or not...)

[IBAUCLAPlaya]

I see you have an 04 too. I have a cat in my turboback and still the stock cat in the uppipe. I threw a P0139 which is rear O2 slow circuit once and I reset my ECU and it hasn't happened in about 800 miles. If you get one just do the mechanical fix.

[hipo_wrx]

i have none and the only thing i worry about is the egt. deleted it and resistored it but i fried one i guess... never threw an o2 sensor code yet