Wiring a 02 sensor

NTK Oxygen sensors are one of the top 2 replacement sensors. The quality is as good as Bosch but much less expensive. I suggest buying the universal 21027 4 wire Mitsubishi replacement sensor. It's about $60 cheaper then the one with the harness and most suppliers have this one in stock. It will require that you use your old harness and wire from the existing O2 sensor. Use the wiring diagram below to match up the new wires to the old. I connected the wires to the sensor before the wiring harness since the old harness was getting old and brittle. Up to you if you want to do it this way.

The O2 sensor comes with heat shrinking crimp connectors with solder in the connector that gives a great weather proof connections.

Wiring details:

The factory O2 sensor has 4 wires: blue, white and 2 black wires. The two black wires are for positive and negative battery connections for the heater in the O2 sensor. (doesn't matter positive or negative for a heater element). The Blue and white wires are for the O2 reading to the computer. Blue is positive and white is Negative. (Don't argue, I'm right. Even though white is usually a positive voltage color it's not with O2 sensors. Go check if you don't believe me)

The NTK sensor has 4 wires: Black, Grey, and 2 white wires. The two white wires are for the heater element. The black and grey wires are for the O2 readings, black is positive and grey is negative. (Don't argue with me, I'm right again)

You can remove the old sensor by cutting the wires and using a 22mm deep socket or using a 22mm wrench (don't use the open end, put the 12pt end over the wires)

The New sensor will have antiseize compound already on the threads covered by a removable plastic cover, be sure not to get the compound on the sensor end.