I have a 97 Dodge RAm 5.2L 4X4 and my check engine light came on. The code is P0138. High Voltage O2 Sensor. My catalytic Converter was removed and i now only have 2 oxygen sensors. I replaced one and the light came back on. Should I replace the other or both and see what happens. Is there only supposed to be 2 sensors? I thought there would be 1 sensor for each bank before the cat and then 1 sensor right after the cat.

 

I had a 96 ram w/ a 360 in it. I re did the whole exhaust, made it totaly custom. The o2 sensors were a pain in my ****. I had 2 o2 sensors, one before the cat, and one after the cat. I took a double in and a double out cat and made my own holes for the o2 sensors and welded on the gromits. For some reason, I had to go through a total of 5 sensors before I had the truck running good and no check engine light. So i'd say take it to a shop that can diagnose wheather its the front or the rear o2 sensor that has gone bad to save you some time and agrivation.

Good luck

 

I believe that you are getting, what I call, a "bad emission" signal from the o2 sensor closest to the cat, or where it used to be. If you have one that monitors the cat (which I believe you do) it is seeing a flow through situation. Do you have emission type inspections? The rear o2 is there for the sole purpose of monitoring the cat and without it, it "sees" the cat as non-functional and I believe that's why you are getting the CEL code. If that is the case, they do make and sell, o2 eliminator packs.