well i just want to tell you this guys. After a bad mileage and trying to do the best with my heavy foot i check the oxygen sensor with my haynes manual info. So after the test the Volt of the both sensor(has oks....before i check it with the dealer computer) and check the 2 heaters(it supposed to have a ressitence 2.3 to 4.3) mine was 7.0 and 6.2(how bad?) so i went to my dealer(theres a friend who is the boss) and he told me with the computer reading....that my O2 sensor is bad...doesnt matter if the cel did pull me any code..cause the sensor was "working ok" but not with the top quality...cause the miles on it(140,000).

So guys if you feel your gas drops a little...just check like the haynes manual says...and you will learns a lot of this.