Q: In my vehicle, the check engine light comes on and then goes off and it is now back on. I had a test done at local auto-parts store that showed a code of PO138. They told me this indicates a ...

Symptoms of a malfunctioning NOx sensor include increased fuel consumption, as well as reduced power and acceleration. If a sensor fails, it will also trigger an on-board diagnostic (OBD) code, ...

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 ...