Ok i have an '02 wrx auto. The car recently threw a CEL and ran horrible. By that i mean it lacked power, idled low (it would dip below 600 rpm and the car would act like it was about to die) oh and it also sounded like a go-kart (like the car went into some kind of limp mode). When diagnosed at local auto shop it read the following codes:
-02 sensor malfunction (bank 1 sensor 2)
I assume the last 3 codes resulted from the 02 sensor malfunction. Well the guy at the auto part store told me that bank 1 sensor 2 was pre-cat, plumbed into the exhaust manifold. I bought the 02 sensor and threw it on 2 days ago. However, the car still runs horrible and once again threw a CEL about 80 miles later. Today i diagnosed the codes and they read:
-02 sensor malfunction (bank1 sensor 2)
I called the local subaru dealership and talked to the parts department. I was informed that bank 1 sensor 2 is actually the midpipe mounted (but still pre-cat) 02 sensor. So the auto part store guy sold me the wrong part, but why did i bother listening to him anyway Well now here is where i am confused. I also have a '95 misubishi eclipse gsx that has a 3" dp w/ no rear 02 sensor (or cat for about 2 years now) and that car runs fine, why would the wrx run so ****ty? could a bad rear midpipe mounted 02 sensor (bank 1 sensor 2) really cause very noticeable lack of power, ****ty idle, and an unexplainable go-kart like growl? I have been searching this site for the last couple days and from what i understand the rear o2 sensor measures catalytic converter efficiency while the front 02 sensor deals with A/F. If that is the case could the rear 02 sensor cause all this headache?