I had a test done at local auto-parts store that showed a code of PO138. They told me this indicates a problem with the oxygen sensor. I replaced the oxygen sensor and the light never went out. I ...

If you want to know more than one thing, you need more than one sensor. In fact, many engines today have not just two oxygen ...

Your vehicle's O2 sensor plays a significant role in its performance and if it's faulty, it's not something you should ignore ...