Bank 1 to lean 2000 nissan ssentra

What was the code? did it end with a 1, that is downstream. Or 4, that is upstream

This codes are for O2 sensor or coolant sensor.

P0171 indicates system lean (bank 1). P0134 indicates no activity from sensor 1 on bank 1. You could have a bad O2 sensor or an actual lean condition. Possible causes of a lean condition include a restricted fuel filter on a vacuum leak.

Bank one is on the side of cylinder one. Cylinder one is typically on the driver side. Although, you have to be careful here. Just because the code mentioned the O2 sensor doesn't mean the sensor is bad. For instance, a code of P0171: sensor indicates lean, bank one sensor; one is not a bad sensor. That is a good sensor telling you that the engine is running lean on bank one. If you get a different code, then it could the be the sensor.

Your sensors are reading correctly so leave them alone. What you have is a fuel delivery issue. Your MAF sensor is telling your engine to lean your fuel mixture. You need to remove and clean or replace (is better) the MAF. But first replace your PVC valve and clean your ERG valve.

It means that your engine is running lean - not getting enough fuel for the amount of air that the engine is receiving. Because your maxima is equipped with a V-6 engine, whatever the problem, it is affecting only bank #1. Bank #1 is always the side of the engine where cylinder #1 is located, or in your case, the left side of the engine as it is viewed while facing the crankshaft end of the engine.
(on a 4 cylinder engine, there is only one bank and it is always referred to as Bank #1)
There are several things that can cause a lean condition including vacuum leaks, a malfunctioning Evaporative Emissions system, a misfiring cylinder (due to bad plugs, bad injectors, or an intake or head gasket leak.), a malfunctioning Mass Airflow sensor (MAF) or Manifold Absolute Pressure sensor (MAP) or even a bad Oxygen sensor (O2s) (Nissan sometimes calls an O2s an "Air-Fuel Ratio Sensor") It is even possible for a leaking vacuum brake booster to cause a lean code.
If there are any other malfunction codes present, it may help to pinpiont the cause of the lean code. (Like a P0301 "cylinder#1 misfire detected", in which case, you would address the misfire code first.)
Certain problems, like a leaking brake booster or a bad MAF will usually set lean codes for BOTH banks.
If the P0171 is the ONLY code present, the most likely cause is a bad O2s, but I recommend some diagnostic testing to prove it before spending the mega-bucks that Nissan gets for their O2 sensors.

bank 1 is the one that has the cylinder number 1 in your engine, if its a 4 cylinder engine its the only one that the engine should have...
the 02 sensor should be on the exhaust manifold, right on the middle of it, going down on the exhaust line
hope this helps

The oxygen sensors in the exhaust pipe are saying the fuel/air ratio is too lean. This commonly happens when the computer in the car reached it's limit putting out the most fuel. Therefore, the mix ratio is still lean.
The possible problem maybe:
The fuel pump not puting out enough pressure.
The fuel filter maybe clogged
The fuel injector maybe clogged or needs to be cleaned.

Were there anymore trouble codes besides the two from Autozone?

this is a lean code bank one the o2 is not the problem it is working because it gave lean code a o2 code would be136 or 138 depending on which one .i would suspect vacuum leak in pcv hose assembly .this a common problem.if you still want to change 02 it will be passenger side upstream 02 which just below exhaust manifold.171 says lean bank one and bank one is the side were #1 cylinder is pass side. i hope this helps and please rate my answer thanks.

sounds like it , the sensor should be on the exhaust somewhere,whith wires on it