I have replaced my o2 sensor 3 times already and this code keeps coming after the first 20-50 miles after I replaced it. Is there anything else I could do? I had the car tuned again as well. Any help would be great.
Thanks

 

I think the answer to my question this code is for the rear o2 on the driver's side. Autozone told me it was before the cat which is wrong. Correct? I thought the rears were tuned out, but maybe the driver's side was forgot about.

 

P0140 is Bank 1, Sensor 2. If they told you precat they were incorrect, or giving you the wrong code.