Nissan Repair: Oxygen Sensor, technical service bulletins, nissan sentra gxe

Question
I've been to 5 different forums, 6 auto parts stores, and 3 Nissan dealerships, and they all have 1 thing in common.  Nobody can seem to figure out which Oxygen Sensor is bank 1 sensor 1 in an 02 Nissan Sentra GXE with the 1.8L engine.

Answer
You have a four cylinder and on a V6 bank one is the front and bank two is the back.  In your case there is only one oxygen sensor in front of the converter and one behind the converter.  The front one is the one you will want.  The back one is to keep people from removing the converter.  Basically, I would change out the front sensor and make sure you run good fuel and keep the oil changed.  The oxygen sensors do not fail that much unless you have over 50K miles on the car.  An oxygen sensor is a self generating device that sends a signal to the computer letting it know how much oxygen is in the exhaust.  The programmers take this into account when they make the engine management software and when the oxygen sensor gets coated with carbon it gets lazy.  That is, it gets slow and this leads to poor performance and bad gas mileage.  In severe cases the computer will throw a code.  So, if you have been running cheap gas or have been going too long between oil changes you could contribute to its early failure.  The moral to the story is use good gas and change the oil regularly.  Use what ever oil you prefer.  Now, I could be full of it and it could just be a defective part.  You can check all the technical service bulletins on your car by going to nhtsa.gov and check for your car.