The cool thing is that you can see these oxygen sensor voltage changes with a scan tool in Live Data mode, and this is how I'm gonna show you how to test them. So, if the voltage output of the O2 sensor stays fixed (when testing it), the O2 sensor has failed. A correctly working O2 sensor will produce a voltage that will switch between a Lean and Rich condition several times every few seconds.This process (of adjusting the amount of fuel injected) by the PCM goes on the entire time the engine is running.When the PCM sees the oxygen sensor voltage below 0.500 Volts, it injects more fuel.This voltage value can go as low as 0.100 Volts DC. The oxygen sensor reacts by producing a voltage below 0.500 Volts.This causes the air/fuel mixture to turn Lean. As the PCM begins to inject less fuel, it may go too far and not inject enough.When the PCM sees the oxygen sensor voltage above 0.500 Volts, it injects less fuel.This voltage value can go as high as 0.900 - 1 Volts DC. The oxygen sensor reacts by producing a voltage above 0.500 Volts.If the PCM injects too much fuel into the cylinders, the air/fuel mixture will turn Rich.The O2 sensor measures how Rich or Lean the exhaust is and reports it back to the PCM. If it doesn't inject enough, the resulting air/fuel mixture is said to be Lean. If the PCM injects too much fuel, the air/fuel mixture turns Rich. The job of the O2 sensor in your 2.4L Nissan Altima (Frontier, Xterra) is to help the PCM (Powertrain Control Module = Fuel Injection Computer) fine-tune the amount of fuel that it injects into the engine. Won't pass state mandated emission testing.P0133 Upstream Heated Oxygen Sensor (O2S11) Circuit Slow Response (Bank 1).P0131 Upstream Heated Oxygen Sensor (O2S11) Circuit Out Of Range Low Voltage (Bank 1).The diagnostic trouble codes lighting up the CEL usually are:.The check engine light (CEL) will be illuminated on your instrument cluster.The effects of a bad oxygen sensor can be very subtle since they usually do not cause serious drive-ability problems. TIP 2: The oxygen sensor test, I'm gonna' show you in this article, is an on-car test, so you do not need to remove it to test it. You don't need the Nissan factory scan tool or an expensive professional technician level scan tool to follow the test procedures in this article, since a simple generic scan tool will do just fine (Don't have a scan tool? Need a scan tool? Check out my recommendation: Actron CP9580 Scan Tool Review).
Your scan tool must have Live Data capability since a simple code reader won't help you. TIP 1: You will need a scan tool to use the testing info in this article.