what codes were you getting and what codes are you getting now? I think that if the codes did not change than you replaced the wrong part. If the codes are different now after changing the O2 sensor, than you probably replaced the right part. Most Indie shops do not have a GT1 computer to connect to your car and they use a accutron reader which gives you codes also. You must remember though that the codes from the accutron give a description of what is wrong but alot of times the description does not pertain to the part that needs replacing. For example, i had a code that described multiple misfires on startup. It did not point to any sensor but it could be anything. I did some research and found out that actually that code was for a CPS sensor. I hope that you actually needed an O2 sensor to begin so you paid for changing a broken part rather than paying to replace the wrong O2 sensor and now paying again to replace the broken O2 sensor.