Add Yahoo as a preferred source to see more of our stories on Google. 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 ...

The "Check Engine" light is the most feared dashboard notification, but for the Oxygen (O2) sensor, it is a lagging indicator. By the time that light illuminates to tell you your O2 sensor has failed, ...

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 ...

When the check-engine light snaps on, it is not a suggestion, it is your car’s way of saying something in the powertrain or emissions system needs attention. I see it as an early warning system that ...