01 nissan pathfinder

Question edited for clarity, add maker.
Question moved to model category.

Your friend is correct, 2 banks, 2 cats, 4 sensors.

https://www.nissanhelp.com/diy/pathfinder/projects/images/2005-2011-nissan-pathfinder-o2-sensor-location-01.jpg

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• Dale, code P0171 fuel system too lean
• Possible causes
• change fuel filter first, if it has not been done recently

RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR
O2 SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
O2 SENSOR HEATER OPERATION
TPS VOLTAGE GREATER THAN 0.92 VOLTS WITH THROTTLE CLOSED
TP SENSOR SWEEP
MAP SENSOR OPERATION
ECT SENSOR OPERATION
ENGINE MECHANICAL PROBLEM
FUEL FILTER/PRESSURE REGULATOR (HIGH)
PCM
Check the attached links,
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2000 Jeep Grand Cherokee p0171

Possible problems related to Code P0171 Jeep Garage Jeep Forum

P0171 System to Lean Bank 1

Code P0171

P1273 Nissan P1273 Nissan - Air Fuel Ratio Sensor 1 Lean Shift Monitoring Bank 1 Possible causes
- Faulty Air fuel ratio (A/F) sensor 1 Bank 1
- Faulty Air fuel ratio (A/F) sensor 1 heater Bank 1
- Fuel pressure
- Faulty Fuel injector
- Intake air leaks
- Faulty Air Flow Meter
Most probable is you have a bad heater in your upper bank 1 O2 sensor. Replace all of your O2 sensors.

Read more: http://engine-codes.com/p1273_nissan.html#ixzz3lgP7CTD8
Read more: http://engine-codes.com/p1273_nissan.html#ixzz3lgOwiMU8

code po105 refers to manifold absolute pressure(MAP)sensor/barometric pressure (BHARO) sensor -circuit malfunction==causes--wiring MAP sensor--BARO sensor--ECM
code p0171 refers to system to lean bank 1===causes intake/exhaust leak---AIR system MAF/MAP sensor fuel pressure /pump /injectors--HO2SW
code p0325 refers to knock sensor(KS) 1 bank 1-circuit malfunction====causes--wiring ---poor connections---KS
Check the exhaust flexible pipe at the manifold for cracks
have a fuel pressure test done on the fuel manifold to determine either pump/ filter or pressure regulator.
replace HO2S unit

OBD=11
code p0171 refers to system to lean---causes ---intake/ exhaust leak---air system---MAF/VAF sensor---fuel pressure/ pump---injectors HO2s
code po105 refers to manifold absolute pressure (MAP) sensor/bar ometric sensor and circuit malfunction causes---wiring---MAP sensor ECM
code p0760 refers to shift solenoid--circuit malfunction causes--shift solenoid---ECM?TCM
code po770 again refers to shift solenoid.
code p0171 again refers to shift solenoid ---performance or stuck off.
code po130 refers to heated oxygen sensor HOS2 1 bank 1-circuit and have the rest checked .malfunction -- causes---heating inoperative---poor connection---wiring--- HO2S. So replace the shift solenoid and oxygen 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.

O2 sensor ? You should change them in pairs. Bank 1 is on driver side.

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.

P0151 Front O2 Sensor, Bank 2 Lean Shift Monitoring,P1168 Closed Loop, Bank 2 i would do the o2 sensor on this side..and thats it unless you get something else

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.