Fit Vehicles:
2011-2012 Nissan Altima 2.5L
Package included:
1pcs MAF Sensor + 4pcs Oxygen Sensors
How does the oxygen sensor in a car work?
The goal of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible.
The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage. The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.
The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.
When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.
Where are my oxygen sensors located?

Diagnostic Trouble Codes (DTC)
When oxygen sensor failure occurs, a DTC is recorded in the Engine Control Unit (ECU) and a Malfunction Indicator Lamp (MIL) is illuminated on the dash, alerting the driver the vehicle has a problem.
Must Know Before Buying:
The following information is for instructional and guidance reference only. We try and make them as accurate as we can.
If Check Engine Light is on or an OBDII Trouble/Fault code occurs after installation, check the sensor with a voltmeter as below. If the sensor is good, further diagnosis is required. There're many different codes for specific functional failures, which are NOT necessarily relevant to the sensor. Find out what the Code means before leaving any feedbacks.
Items that have been installed, altered or contaminated are non-returnable.
A. ONLY a defective sensor after tested by a voltmeter is applied to manufacturer warranty.
A. 20% restocking fee is required if buyer bought wrong items due to not paying attention to fitment information and ask for return.
The Price, Quality & Functionality of the O2 Sensor is fully covered under our warranty & return policy. However, refund for any labor cost, expense in a dealer shop or damage due to wrong installation is NOT covered.
Q: How do I know the O2 sensor is good or not?
https://www.youtube.com/watch?v=ToRGk05_EV4
A: The only way to know if the O2 sensor is functioning normally is to check its responsiveness to changes in the air/fuel mixture, by Voltage Measurement or Waveform Simulation.
Use a 10-megaohm digital voltmeter. Hook up the voltmeter's red probe to the sensor's signal wire and the black probe to engine ground. (Use back probe method, DO NOT pierce the wire.) For a good sensor, voltage should fluctuate constantly between 0.1 and 0.9 volts after starting the engine for 2 or 3 minutes.
Please take a video clip of the voltmeter and contact us if our sensor:
Goes above range between 0.1 and 0.9 volt
Remains below 0.5 volts
Stays fixed at a particular voltage
You're free to choose replacement or refund if our sensor fails to work, in this case.