How can someone tell if there oxygen sensor is faulty? I'm having problems with the idling and black smoke out the exhaust could this be the problem.

 

I think you need a special tester thing.

I don't think there is anything you can do really. How do you know thats what is causing it?

 

I did change both the O2 sensors and sure enough thats what it was , now runs great and no more black smoke, Because the O2 sensor was bad it wasen't sending the right info to the computer so it wasent getting the right air to fuel mixture and this is why it was smoking, to much fuel.