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 ...

The oxygen sensors on your Toyota Celica help determine if the air-fuel ratio of the engine is rich or lean. This helps the electronic fuel injection adjust the mixture in real time and also reduce ...

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 ...