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, ...

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 ...

Oxygen sensors play an important role in your car's engine, but they aren't like many other components, such as oil filters, for which automakers provide a strict service schedule. Instead, the real ...

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 ...