p0138 code

[nohez8n]

Being have a problem over the last few months with my 01 GXE. I can ride around town for weeks with no CEL, but as soon as I drive above 60 on the highway for more than 30 minutes the CEL light will come on and it is throwing a code P0138. Should I be concerned because the car is running great and gas mileage is not suffering. Nissan wants almost $300 to replace the O2 sensor and they said that this may not even fix the code. I know that you can buy the sensor on the net for about $90, but I am not sure if I can change it myslef. I guess my question is " Will it hurt the car to not change the sensor and if I decide to do it myslef will it be more than I can handle. Thanks for the feedback.

[maxhopper]

Buy the Denso sensor from http://www.sparkplugs.com (NICO Sponsor, and price I've found). Don't get a universal one that has to be soldered to the OEM plug.

Directions on replacing the O2 can be found here (yours will be slightly different). zerothread/185176