need help i'm trying to fix my car and l bought 4 universal oxygen sensor it has 2 sensors (downstream) 4 wires
2 (upstream) 3 wires, now how can l locate the colors of the each sensor.
here are the colors one is red the others are like blue or gray and so on
and also from where i'm standing in front of the car left to right
where is Bank 1 sensor 1, Bank 1 sensor 2, Bank 2 sensor 1,Bank 2 sensor 2 please help l already got them wired
i just need to install them back

you should have gone with the original ones for the car are you sure they will work with the computer l would have never put universal ones on stay with stock you would not have had so much problems

First off, you should have gone and bought the Nissan O2 sensors. You will have problems with the universal ones as they do not have the same specifications as the Nissan O2 sensors. Secondly, you have a 4 cylinder engine not a 6 cylinder. There is not a bank 2. Take the sensors back and get the right ones from Nissan. You should only need 2 sensors.