If your Check Engine light is constantly trying to get your attention, one possible problem could be a bad O2 sensor. If you do have a failed oxygen sensor, follow these steps to replace it.

The oxygen sensor was replaced but the 'check engine' light won't go out. Now what? Which octane fuel is best? AAA's Car Doctor has answers.

A-The oxygen sensor on your car is in the exhaust manifold close to the spot at which the extension pipe connects to the engine. If the sensor is working properly, there is no need to replace it ...

As mentioned above, they monitor oxygen levels and feed the information to the onboard computer, which adjusts everything accordingly. Move the O2 sensor out of the picture, and your vehicle will not ...

Should that be the case for your vehicle failing an emission test, it is worth inspecting the O2 sensor for malfunctioning, the injectors for leaks, or a worn-out fuel pump.

Rounding out the five most common problems found to trigger the check engine light after ignition coil and spark plug, and O2 sensor were 3) catalytic converter, 4) loose or damaged fuel cap and 5 ...

The oxygen sensor was replaced but the 'check engine' light won't go out. Now what? Which octane fuel is best? AAA's Car Doctor has answers.