The code number would be helpful in determining what your problems is, But the V6 has a bank 1 and a bank 2. There is 1 upstream, and 1 downstream sensor for each bank. Your fault seems to be with the upstream (before the pre-cat) sensor on the bank that is closes to the firewall. This is hard to reach but can be replaced in about 20 minutes following the info in the how-to section of the main CEG page. A code reader can not eliminate bad sensors. It can only read (& clear) the fault codes caused by improper readings from these sensors. If the sensor is bad, the fault will just come back again. Upsteam sensors seem to go out most often and cost about $60 at autozone who can read your codes for free.
