2000 nissan maxima, runs great, engine lite on, won't pass emissions

You have 2 of them,one in the exhaust manifold,the other after the cataylac converter.

It will not pass inspection.
P0325 NISSAN - Knock Sensor Circuit Malfunction http://engine-codes.com/p0325_nissan.htmlForum CodePossible causes- Faulty knock sensor
- Knock sensor circuit short to ground
- Knock sensor circuit short to power
- Knock sensor circuit open
- Faulty Engine Control Module (ECM) Tech notes Very common problem with Nissan vehicles. Replacing the knock sensor usually takes care of the problem.

renew the O2 sensors to start with and just hope that its a bad sensor on this bank they can break down prematurely .Luck of the draw their when buying new parts iam afraid your not the only one to buy new parts and have them go early .

Codes do not tell you what to replace
They only tell you that a malfunction occured
Does not mean anything need replacing
Example: if you got an O2 Sensor code from a loose
vacuum hose ,would you change the sensor.
Most people would. I would diagnose and repair the hose,
letting in the extra oxy and leaning out my sensor.

What where the Emission Readings?

What did it fail for
HC,CO,NOX

If the car is pinging you will set a knock sensor code.'
This comes from bad gas and running lean., You really need this professionally inspected to rule out the basics. I have seen alot of nissans with the knock sensor code stored but the light is still off.
Fill up the tank with high octane chevron and some techron injector cleaner and clear the light. If it stays off for a couple days then go get it inspected. Even if the code is stored it will still pass as long as the light is still off and the monitors have run.

P0136 indicates a bad O2 sensor. This reports poor emission performance back to the car's PCM (computer)
P0325 indicates a bad "Knock" sensor which would adversely effect drivability as far as performance is concerned. Only way to fix these 2 problems is replacement of the 2 components.

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.

catalytic converter is the way to fix your problem because they do an emissions test and the code want go away even if you get the light off before you take it in they will no the computer has just been reset so which means all the sensors want have enough info to give the computer because of being reset sorry to break it to you.

The Crankshaft Position Sensor is located: Under hood, driver side, front engine area, mounted rear of crankshaft pulley
The Knock Sensor is located: Under hood, center, front engine area, below intake manifold, mounted on block