OBD II scanner was showing code P0174, and I was getting very poor gas mileage. This is for the drivers side (Bank 2), which I confirmed by testing the current sensor with a multimeter, and found it was reading much lower then the passenger side sensor. I recommend replacing both at the same time. I also replaced the nut washer that the sensor screws into, which then screws into the exhaust. I used a regular oxygen sensor wrench, which also sometimes removes the nut from the exhaust, and then had to use a bench vise to get the exhaust nut off the sensor.

Nut P/N: 20607-P6500

New sensors for trucks in the 01-04 range should read about 6.5 Ohms. Move the black wire on your multimeter to the ohm connector and set it to 200 ohms. Just unplug the connection on the top of the motor, to test without needing to remove the sensor. Test the two outside wires in each sensor side plug. I was getting P0171 on my old Frontier, and that also was resolved by replacing the passenger side (Bank 1) heated oxygen sensor.

The complete list of items used in this project, and other projects, can be found in the Parts List below.